Block-copolymer self-assembly: fundamentals and applications
Self-assembly of block copolymers can be used to design and control the shape and dimension of resulting nanostructures. The versatility and scalability of this method makes them highly attractive for the synthesis of advanced materials. They represent a potent platform for fundamental studies at the nanoscale and application-driven investigation.
The symposium focuses on the self-assembly of block copolymers, reporting recent advances in the understanding of their basic properties and latest progresses towards their technological exploitation.
Block copolymers can hierarchically self-assemble into chemically distinct domains with size and periodicity on the order of 10-100 nm, offering a potentially inexpensive route to generate large-area nanostructured materials. A large variety of distinct periodic morphologies (spheres, cylinders, lamellae and gyroids) can be obtained by proper selection of the macromolecules. The final structure characteristics of these materials are dictated by the properties of the elementary block copolymers, like chain length, volume fraction or degree of block incompatibility.
Modern synthetic chemistry offers the possibility to design these macromolecules with very specific length scales and geometries, directly embodying in the macromolecules the “code” that drives their self- assembling process. However, much remains unknown about the ultimate capabilities of block-copolymer self-assembly, especially as new materials push the limits of size, fidelity, and complexity. The understanding of the kinetics and thermodynamics of the block copolymer self-assembly process in the bulk phase as well as in thin films represents a fundamental prerequisite toward the exploitation of these materials as a tool for the fabrication of functional nanostructured materials. Incorporating block copolymer into device fabrication procedures or directly into devices, as active elements, will lead to the development of a new generation of devices fabricated using the fundamental law of nature to our advantage in order to minimize cost and power consumption in the fabrication process.
In the next coming years this area of research, at the intersection between fundamental science and technology, is expected to disclose additional insights in the physics of the self-assembly process and to delineate unforeseen applications for these materials. The workshop is expected to define a platform for the discussion of the main challenges in this research field bringing together scientists, engineers and students working on all the aspects of block copolymer self assembly, from fundamental physics and chemistry issues to the final application in functional devices.
Within the symposium a special session will focus on directed self-assembly (DSA) of block copolymer thin films for advanced lithographic applications. This focus session will offer the possibility to discuss specific aspects related to the development of a block copolymer based technology for the fabrication of sub 20 nm features in microelectronics. This event is organized in the framework of the European project IONS4SET (www.ions4set.eu)
Hot topics to be covered by the symposium:
- Synthesis of new block copolymer materials
- Theory, modeling, and simulation of the self-assembly of block copolymers
- Block copolymer self-assembly for lithographic applications
- Conductive and ionic block copolymers for electronic, optoelectronic and photovoltaic applications
- Block copolymers for membrane fabrication
- Metrology of block copolymers
- Directed self-assembly of block copolymers
- The controlled assembly of block copolymers in solutions, in the bulk, and in thin films
- Kinetics and thermodynamic equilibrium of block copolymers
List of confirmed invited speakers:
- Jillian M. Buriak, University of Alberta
- Teruaki Hayakawa, Tokio Institute of Technology
- Igor I. Potemkin, Lomonosov Moscow State University
- Yeon Sik Jung, Korea Advanced Institute of Science and Technology (KAIST)
- David Jones, University of Melbourne
- Thomas H. Epps III, University of Delaware
- Xavier Chevalier, Arkema
- Pawel Majewski, Warsaw University
- Jin Kon Kim, Pohang University of Science and Technology
- Marleen Kamperman, Wageningen University & Research
List of scientific committee members:
- Sang Ouk Kim, Korea Advanced Institute of Science and Technology (KAIST)
- Ileana A. Zucchi, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
- Raluca Tiron, Technology Research Institute LETI
- Gabriele Seguini, Institute of Microelectronics and Microsystems (IMM-CNR)
- Michele Laus, Università del Piemonte Orientale
- Christopher K. Ober, Cornell University
- Peter Müller-Buschbaum, Technische Universität München
- Marcus Mueller, Georg-August University
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Authors : Michele Perego (1), Morgan Stefik (2), Guillaume Fleury (3), Francesc Perez-Murano (4)
Affiliations : (1) Laboratorio MDM, IMM-CNR, Via Olivetti 2 Agrate Brianza Italy (2) University of South Carolina Department of Chemistry and Biochemistry - 541 Main st, Columbia, SC 29208, USA (3) University of Bordeaux, LCPO 16 avenue Pey Berland, 33607 Pessac Cedex, France (4) Institute of Microelectronics of Barcelona (IMB-CNM, CSIC) Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
Resume : Introduction to Symposium M
Self-Assembly Process - I : Morgan Stefik
Authors : Jinwoo Oh, Jeong Gon Son
Affiliations : Korea Institute of Science & Technology
Resume : Achieving sub-10 nm high-aspect-ratio patterns from block copolymer (BCP) self-assembly requires both a high interaction parameter and a perpendicular orientation of microdomains. However, these conditions are difficult to achieve simultaneously because the blocks in a high-? copolymer typically have very different surface energies, favoring in-plane microdomain orientations. We introduce top coat for the control of orientation, alignment and morphology of BCP thin films. Using partially hydrolyzed PVA top coats with a solvent annealing, perpendicular orientation of PS-b-PDMS can be obtained despite the large surface energy differences between PS and PDMS. Extremely straight and laterally aligned cylindrical microdomain of BCP films were prepared by simply covering the BCP films with a top coat and dewetting the latter via thermal annealing to generate shear flow in the BCP underlayer. We also observed the gyriod-cylinder phase transition using interfacial-energy-tailored top-coat. At the optimized top-coat composition, gyroid nanostructures with sub-10 nm strut width were achieved down to ?125 nm. Secondly, for the superior thermoelectric properties of graphene and conducting polymers, we also briefly introduce sub-10 nm graphene nanomesh structures and in-situ vapor phase polymerization of PEDOT:Tos on highly ordered lamellar, cylindrical and disordered nanostructures from block copolymer/oxidant blended films.
Authors : Elena E. Dormidontova
Affiliations : Polymer Program, Institute of Materials Science and Physics Department, University of Connecticut, 97 North Eagleville Road, Storrs, CT 06269, USA
Resume : Diblock copolymer self-assembly has been a subject of active studies with considerable progress made in understanding the principles of equilibrium self-assembly. Kinetics of self-assembly or chain exchange are influenced by different factors starting from hydrophobicity and chain length to chain architecture. Computer simulations can provide molecular level insights which are often difficult to access experimentally. We’ll discuss different factors influencing chain exchange kinetics based on results of dissipative particle dynamics simulations and compare the finding to experimental data. In particular, the effect of chain architecture and conformation will be considered with the example of diblock copolymers with a ring-shaped core or corona block in comparison with their linear diblock copolymer counterpart. We found a striking difference in both the equilibrium micelle size and kinetics of chain exchange in these systems. Furthermore, mixed micelles containing block copolymers of both types while having similar size and shape to linear diblock copolymers, possess different chain exchange kinetics, which exhibit synergism of chain exchange. The origin of this effect and its implication for micelle self-assembly and practical applications of self-assembled nanostructures will be discussed.
Authors : Shengxiang Ji
Affiliations : Changchun Institute of Applied Chemistry, Chinese Academy of Sciences
Resume : Random copolymer brushes have been widely used to control the wetting behaviors of block copolymers (BCPs), but random copolymerization is only limited to a few monomer pairs. Here we demonstrate the use of homopolymer brushes to modify the substrate to form a chemically homogeneous surface. The surface affinity is tuned by changing the monomer substituent, and a variety of wetting behaviors are obtained in BCP films on homopolymer brushes. Three series of hydroxyl-terminated or crosslinkable homopolymers, including polymethacrylate, polyacrylate and polystyrene derivatives, are prepared for controlling the BCP-substrate interaction. Both preferential and non-preferential wetting behaviors of PS-b-PMMA, PS-b-PLA and PS-b-PPC films are obtained as the homopolymer structures change in terms of the carbon contents. Moreover, homopolymer brushes can also substitute random copolymer brushes in directed self-assembly of BCP films with density multiplication on chemical pattern. The use of homopolymer brushes may have advantages over random copolymer brushes in terms of reproducibility and uniformity of brush formation, reduction of defect density and increase of assembly kinetics.
Self-Assembly Process - II : Michele Perego
Authors : Jillian M. Buriak, Cong Jin, Brian C. Olsen, Erik J. Luber
Affiliations : Department of Chemistry and National Institute for Nanotechnology, University of Alberta, Edmonton, AB, Canada, T6G 2G2
Resume : The self-assembly of block copolymers is a cost-effective method for large-scale, high-resolution nanopattern fabrication. Typical patterns include hexagonal dots and parallel lines, but through additional of chemical and/or topological features, more complex patterns can be produced. In this work, we describe an entirely bottom-up approach that yields Moiré superstructures through a two-step process involving two sequential self-assembly steps of incommensurate block copolymer dot arrays. Preferential orientation of the two hexagonal arrays is observed due to a registration force exerted by the first layer on the second, leading to the large-area Moiré patterns. Statistically meaningful data, derived from helium ion microscopy imaging, revealed specific size regimes where interlayer registration forces can induce long-range preferential alignment of these incommensurate block copolymer dot array patterns. As is typically the case with block copolymer self-assembly, subtle effects can play critical roles, including factors such as dot size, grain boundaries between dot domains, and the annealing process - the potential, and limitations, of this approach for making higher order nanoscale patterns will be described.
Authors : Karolina Korzeb1, James Dolan2, Narjes Abdollahi1, Cédric Kilchoer1, Ulrich Wiesner3, Ullrich Steiner1, Bodo D. Wilts1, Ilja Gunkel1
Affiliations : 1 Adolphe Merkle Institute, University of Fribourg, 1700 Fribourg, Switzerland; 2 Institute for Molecular Engineering, University of Chicago, Chicago, IL, United States; 3 Department of Materials Science and Engineering, Cornell University, Ithaca, NY, United States;
Resume : Gyroid terpolymer films can serve as templates for the fabrication of a range of 3D functional nanostructures including optical metamaterials. These plasmonic materials can show interesting optical properties - a nanostructured gold gyroid, for example, was demonstrated to exhibit a linear dichroism. However, these anisotropic optical properties can only be observed in materials that were fabricated using gyroid terpolymer templates with long-range order, the generation of which still remains challenging. In this work, we show that gyroid structures with grains of about 5-15 µm in size can be generated by means of controlled solvent vapor annealing of a polyisoprene-b-polystyrene-b-poly(glycidyl methacrylate) (ISG) triblock terpolymer film. In situ grazing-incidence small-angle x-ray scattering (GISAXS) was employed to identify the order-disorder transition in terpolymer films during annealing in the vapor of tetrahydrofuran. Gyroids with long-range order were produced by slowly removing the solvent from swollen ISG films in the ordered state. Interestingly, these terpolymer films exhibit alternating gyroid morphology with a previously unreported out-of-plane orientation along the  direction. Gold gyroids replicated from ordered ISG terpolymer films feature interesting optical properties relevant for future design strategies of optical metamaterials.
Authors : Gabriele SEGUINI, Fabio ZANENGA,[1,2] Michele LAUS, Michele PEREGO
Affiliations :  Laboratorio MDM, IMM-CNR, via C. Olivetti 2, 20864 Agrate Brianza (Italy)  Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale ?A. Avogadro?, INSTM, UdR Alessandria, Viale T. Michel 11, 15121 Alessandria, Italy
Resume : The all-organic polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) BCP thin films have been widely investigated for advanced lithographic applications, due to possibility to promote perpendicular orientation of the nanodomains by easy neutralization of the surface with the appropriate poly(styrene-random-methyl methacrylate) P(S-r-MMA) random copolymer. Because the XS-MMA parameter is weakly dependent on T, fundamental studies on the self-assembly and grain coarsening processes can be performed modulating the segregation strength XN by simply changing the degree of polymerization N. In this work the grain coarsening process in thin films of asymmetric cylinder forming PS-b-PMMA BCP with degree of polymerization, N, ranging from 461 to 1281 (molecular weight: 48-132 kg/mol) was accomplished by fine tuning of the annealing temperature (TANN = 140-290 °C) and time (tANN = 1-900 s) in a rapid thermal processing machine. Hexagonally packed PMMA cylinders perpendicularly oriented with respect to the substrate with different level of lateral order were obtained. The evaluation of the correlation length allows determining the growth exponent f and the activation enthalpy HA for each N. For the lowest N, f saturates at ?1/3. This value equals that of systems that coarsen with a diffusion-limited mechanism. Increasing XN, both f and HA decrease following an exponential decay as a function of N with exponent ?XS-MMA. This dependence exactly mimics that of the chain diffusivity.
Authors : Marta Fernández-Regúlez(1), Laura Evangelio(1,2), Steven Gottlieb(1), Gemma Rius(1), Jordi Fraxedas(2) , Francesc Perez-Murano(1), Heinz Amenitsch(3), Edgar Gutiérrez(4), Aurora Nogales(4), Mari Cruz García-Gutiérrez(4), Tiberio A. Ezquerra(4)
Affiliations : (1)Institut de Microelectrònica de Barcelona (IMB-CNM, CSIC), Campus UAB, Bellaterra 08193, Barcelona, Spain; (2)Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain; (3) Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/5, A-8010 Graz, Austria; (4)Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, Madrid 28006, Spain;
Resume : Directed self-assembly (DSA) of block copolymers (BCP) is considered by the semiconductor industry as one of the main alternative for next generation technological nodes. Further advances towards the incorporation of DSA-based technologies require a deep understanding of the self-assembly mechanism to find optimal process conditions (i.e. kinetics of self-assembly) and decrease the defect density. In order to evaluate the potential of BCP-based technologies, new metrology methods with sufficient spatial resolution and capable to probe large analysis areas for statistical studies must be applied. In this scenario, grazing incidence small-angle X-ray scattering (GISAXS) is a reliable method for its high spatial resolution and fast temporal response over large scanning areas. In this contribution, we show the characterization of dynamics of thin film BCP self-assembly processes by GISAXS. First, the self-assembly of different PS-b-PMMA systems has been studied in real time by thermal annealing while GISAXS data is recorded (i.e. in-situ testing). Different annealing conditions have been analyzed, allowing us to monitor the order-disorder transition of the BCP films. Furthermore, this technique has been also used for the characterization of sequential infiltration synthesis (SIS). An evolution of the maxima at Yoneda band was observed in the samples attributed to the incorporation of aluminium oxide into the PMMA block, as a function of number of cycles and process conditions.
Authors : Jonathan G. Raybin (1), Julia G. Murphy (1), Jiaxing Ren (2), Moshe Dolejsi (2), Xuanxuan Chen (2), Roel Gronheid (3), Paul F. Nealey (2), and Steven J. Sibener (1)
Affiliations : (1) The James Franck Institute and Department of Chemistry, The University of Chicago; (2) The Institute for Molecular Engineering, The University of Chicago; (3) imec, Leuven, Belgium;
Resume : Video-rate atomic force microscopy (AFM) provides a new paradigm for studying the evolution of block copolymer (BCP) self-assembly during the thermal annealing process. We use real-time, environmentally controlled AFM to examine the dynamics of BCP patterns on the time scale of individual microdomain connections to achieve direct visualization of defect healing mechanisms. This highly general technique has been applied to several systems fundamental to understanding polymer dynamics. First, we have tracked defect healing and pattern alignment of BCP thin films on chemically templated substrates. We observe that pattern evolution is mediated by the presence of a novel, metastable BCP superstructure. Strikingly, the chemical template caused alignment of these films to occur irreversibly. Second, we have monitored spatial fluctuations of BCP domains during thermal annealing. Such fluctuations give rise to line-edge roughness and line-width roughness which currently limit the applicability of BCP templates for device fabrication. We find that fluctuations also play an intrinsic role in controlling the defect rates of patterned films.
IONS4SET Workshop: Directed Self-Assembly - I : Jilian Buriak
Authors : X. Chevalier,a,* C. Nicolet,a G. Fleury,b , M. Zelsmann,c P. Bezard,c A. Legrain,c C. Navarro,a D. Jurajda,d I. Cayrefourcq,e
Affiliations : a. ARKEMA FRANCE, Route Nationale 117, BP34- 64170 Lacq, France. b. LCPO-UMR 5629 Université Bordeaux I-CNRS, 33405 Talence cedex, France. c. LTM-CNRS, Minatec Campus, 17 rue des Martyrs, 38000 Grenoble, France. d. Brewer Science Inc., 2401 Brewer Drive, Rolla, MO 65401, USA. e. ARKEMA FRANCE, 420 rue d’Estienne d’Orves, 92705 Colombes, France.
Resume : The directed self-assembly (DSA) of block-copolymers (BCP) is now established to be a straightforward technology to further decrease limits currently achievable by conventional lithographic tools. Indeed, the capabilities of these materials to form homogeneous self-assembled structures of different shapes of small sizes over large areas make them attractive for sub-10nm patterning.1 In this contribution, we will first highlight the patterning performances for the two strategies specifically developed to improve self-assembly defectivity and kinetic, illustrated on the basis of PS-b-PMMA systems. These approaches, namely blended-materials2 and Special3 BCPs, will be benchmarked through the key DSA material properties (film-thicknesses, defectivity, CDU, …) versus regular PS-b-PMMA BCPs of same dimensions, in order to evidence their improved characteristics and the potential benefits of using such approaches in microelectronic applications. Then, we will present the properties of various materials developed to further reduce the dimensions achievable with PS-b-PMMA BCPs. These high-χ silicon-containing BCPs, based on PDMSB-b-PS architecture,4 can be self-assembled under a standard thermal bake to form perpendicular features, either on neutral free-surfaces or once guided in templates. Thanks to the silicon contained in one phase of the BCP, the features obtained can be transferred into the substrate with high aspect-ratios, rendering thus these materials attractive for patterning applications. References: 1. H.-C. Kim &al., Chem. Rev. 2010, 110, 146. 2. X. Chevalier &al., Proc. SPIE 9049, Alternative Lithographic Technologies VI, 90490T (March 27, 2014). 3. X. Chevalier &al., Proc. SPIE 9779, Advances in Patterning Materials and Processes XXXIII, 977913 (March 25, 2016) 4. A. Legrain &al., ACS Appl. Mater. Interfaces 2017, 9, 43043.
Authors : Johannes von Borany, Karl-Heinz Heinig
Affiliations : Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
Resume : Single electron transistors (SETs) operating at room temperature (RT) are promising candidates for low power electronics needed for Internet of Things. The IONS4SET project aims to realize SETs on the basis of single Si nanodots (Si NDs) in the centre of thin SiO2 layers, which are part of vertical nanopillars etched out of a Si/SiO2/Si layer stack. For RT operation, tiny Si NDs (< 3 nm) with high Coulomb blockade energy are necessary. Moreover, to ensure enough current by quantum mechanical tunneling, the Si NCs have to be exactly located in the oxide at distances to source and drain of ~ 1…2 nm. We employed self-assembly of Si NDs where ion beam mixing transfers SiO2 to SiOx and subsequent phase separation forms the Si NC in the c-Si/SiO2/a-Si nanopillar. Predictive computer simulations and energy-filtered transmission electron microscopy demonstrate the self-assembly of Si NDs with targeted dimensions. Formation of single Si NDs requires mixing/phase separation to be performed in nanopillars with volume < 1.000 nm³. Experimentally two different approaches are currently under investigation to fabricate these tiny structures. A conventional top-down approach based on e-beam lithography is tested together with a bottom-up solution based on directed self-assembly of block copolymers. An overview of current achievements of the project will be presented. This activity is funded by the European Union’s Horizon 2020 research and innovation program under grant agreement No 688072.
Authors : Federico Ferrarese Lupi 1, Tommaso Jacopo Giammaria 2,3, Andrea Miti 4, Giampaolo Zuccheri 4, Stefano Carignano 5, Natascia De Leo 1, Michele Perego 2, Michele Laus 3
Affiliations : 1 Nanoscience and Materials Division, Istituto Nazionale Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy 2 CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, 20864 Agrate Brianza, Italy 3 Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale ‘‘A. Avogadro’’, Viale T. Michel 11, 15121 Alessandria, Italy 4 Dipartimento di Farmacia e Biotecnologie e Istituto di Nanoscienze del CNR (S3-Modena), Via Irnerio, 48 , 40126 Bologna, Italy 5 LNGS–INFN, Via G. Acitelli, 22, 67100 Assergi,Italy
Resume : Block Copolymers (BCPs) are attracting wide interest for advanced lithographic applications due to their ability to self-assemble into well-ordered nanometric size structures. In this work we investigated the influence of interfacial energy and BCP film thickness (hBCP) on the dewetting mechanisms and the self-assembly properties of thin films of asymmetric PS-b-PMMA BCP. In particular, the control over γ was achieved by grafting to the substrate a random copolymer layer with thickness between 2 and 7 nm, while the morphology of the dewetted structures was studied by tuning hBCP. For hBCP < 10 nm the BCP films dewet generating holes, bicontinuous structures or circular droplets. In addition, chemically patterned substrates obtained by laser writer lithography were used direct the ordering of the dewetted droplets, providing a simple route to the fabrication of hierarchically self-assembled nanostructures. The formation of highly ordered self-assembled features inside the dewetted film, organized in single and defectless grains propagating for several micrometers was observed. Respect to other surface-directed dewetting approaches, the present procedure guarantees a significantly higher level of ordering of the nanometric cylinders while maintaining their perpendicular orientation to the substrate.
Authors : A. Paquet, A. Gharbi, C. Navarro, C. Nicolet, X. Chevalier, K. Sakavuyi, K. Xu, L. Pain, I. Cayrefourcq, R. Tiron
Affiliations : A. Paquet - Arkema - CEA LETI; A. Gharbi - CEA LETI; C. Navarro - Arkema; C. Nicolet - Arkema; X. Chevalier - Arkema; K. Sakavuyi - Brewer Science; K. Xu - Brewer Science; L. Pain - CEA LETI; I. Cayrefourcq - Arkema; R. Tiron - CEA LETI;
Resume : New emerging lithography approaches are promising technologies, among which Directed Self-Assembly of block copolymer, also called “DSA”. In order to favour block copolymer orientation with a long range order, one of the widest used technics is the chemo-epitaxy. It orientates the block copolymer thanks to a chemical contrast of predefined periodic patterns based on a difference of the surface energy. Among all the different chemo epitaxy processes developed (Line , SMART , Lift-Off , COOL  ) the selective grafting of the guiding material with regards to the background layer remains a key challenge: it has to be fully effective after grafting without modifying the background layer, especially in terms of the surface energy. This paper investigates different materials families for a chemo-epitaxy application, that is to say cross-linked and grafting underlayers of different chemical properties (composition, molecular weight…), and the effect of a grafting material at their surface. In order to illustrate the results obtained, a proof of concept on a new innovative chemo-epitaxy process using spacer patterning lithography is introduced. The latter process has the advantage to integrate high chi block copolymers with the conventional lithography targeting sub-20nm pitch line/space patterns.  C.-C. Liu et al., “Fabrication of Lithographically Defined Chemically Patterned Polymer Brushes and Mats,” Macromolecules, vol. 44, no. 7, pp. 1876–1885, Apr. 2011.  J. Kim et al., “Toward high-performance quality meeting IC device manufacturing requirements with AZ SMART DSA process,” 2015, p. 94230R.  J. Y. Cheng et al., “Simple and Versatile Methods To Integrate Directed Self-Assembly with Optical Lithography Using a Polarity-Switched Photoresist,” ACS Nano, vol. 4, no. 8, pp. 4815–4823, Aug. 2010.  Y. Kasahara et al., “Characterization of half-pitch 15-nm metal wire circuit fabricated by directed self-assembly of polystyrene-block-poly(methyl methacrylate),” Microelectron. Eng., vol. 159, pp. 21–26, Jun. 2016.
Authors : E. Cianci (1), D. Nazzari (1,2), G. Seguini (1), M. Perego (1)
Affiliations : (1) IMM-CNR, Agrate Brianza Unit, via C. Olivetti 2, 20864 Agrate Brianza (MB), Italy; (2) Department of Physics, Università Statale di Milano, Via G. Celoria 16, 20133, Milano (Mi), Italy
Resume : Challenges for sub-10 nm patterning can be addressed by the direct self-assembling of block copolymers (BCP) in combination with a volume selective sequential infiltration synthesis (SIS). Selective growth of inorganic materials in one of the BCP domains can be used for enhancing polymer etch resistance for pattern transfer to the substrate. We investigated the infiltration of trimethylaluminum (TMA) in combination with H2O for the synthesis of Al2O3 into polymethylmethacrylate (PMMA) and polysterene (PS) films, being the building blocks of PS-b-PMMA BCPs, by means of dynamic in situ spectroscopic ellipsometry. In particular, swelling of the polymer films is probed during SIS cycle, and observed to be affected by SIS process parameters as TMA dosing and purging, but also by the history of the polymer for SIS cycles following the first one. Investigating the swelling of fresh PMMA films during TMA infiltration at 90°C, the diffusion coefficient of TMA in PMMA has been extracted and shown to be dependent on polymer molecular weight but not on the film thickness, indicating a Fickian behavior for diffusion of TMA in PMMA films. Differently, PS films swelling is almost negligible during TMA exposure and after the first 3 complete SIS cycles reflecting the inertness of PS to TMA molecules, while for many SIS cycle process, swelling increases and some Al2O3 growth is observed also in PS films, attributed to defects in the film, leading to loss of infiltration selectivity.
IONS4SET Workshop: Directed Self-Assembly - II : Xavier Chevalier
Authors : Teruaki Hayakawa
Affiliations : Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-S8-36 Ookayama, Meguro-ku, Tokyo Japan
Resume : Block copolymers (BCPs) which are able to spontaneously self-assemble into discrete nanostructures have been proposed as a promising candidate for next generation nanopatterning technologies, namely directed self-assembly (DSA), enabling high-resolution patterning in thin films over large areas at low cost. Silicon-containing BCPs have garnered significant attention for achieving sub-10 nm feature sizes required for next generation lithography techniques. In addition, the high etching contrast between the hydrocarbon polymer block and the silicon-containing polymer block allows for facile pattern transfers to substrates upon oxygen plasma etching. However, the hydrophobicity and lower surface energy of the silicon-containing polymer block prevents the lamellar structure from forming with a perpendicular orientation that is vital for line patterning lithography. In this study, a series of perpendicular lamellae-forming high-chi block copolymers have been developed based on the bottom-up concept of a simple yet effective material that adjusts the chemical properties and molecular composition of the material. One example is newly designed and successfully synthesized silicon- and fluorine-containing high-chi BCP, poly(polyhedral oligomeric silsesquioxane-block-2,2,2-trifluoroethyl methacrylate) (PMAPOSS-b-PTFEMA) whose surface free energies of the constituents are perfectly balanced. The perpendicularly oriented BCP thin films were fabricated using simple spin-coating and thermal annealing processes under ambient conditions. The thin films displayed a minimum domain size of L0 = 11 nm. The formation of microphase-separated nanostructures were observed in in-situ Atomic Force Microscopy.
Authors : S. Gottlieb (1), D. Kazazis (2), I. Mochi (2), L. Evangelio (1), M. Fernández-Regúlez (1), Y. Ekinci (2), F. Perez-Murano (1)
Affiliations : 1: Instituto de Microelectrónica de Barcelona IMB-CNM, CSIC, 08193 Bellaterra, Barcelona, Spain; 2: Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
Resume : The International Technology Roadmap for Semiconductors ITRS considers the directed self-assembly (DSA) of block copolymers as one of the four next generation lithography techniques. Guiding patterns are required to induce long-range order in a thin film of block copolymers and to enable the use of block copolymers for lithography applications. Extreme ultraviolet interference lithography (EUV-IL) is used to manufacture topographical guiding patterns to direct the self-assembly of block copolymers. High-accuracy silicon oxide-like patterns with trenches ranging from 68 nm to 117 nm width are fabricated by exposing a hydrogen silsesquioxane (HSQ) resist layer using EUV-IL. We investigate how the accuracy, the low line width roughness and the low line edge roughness of the resulting patters allow to achieve DSA line/space patterns of a PS-b-PMMA (polystyrene-block-poly methyl methacrylate) block copolymer of 11 nm half-pitch with low defectivity. We conduct an in-depth study of the dependence of the DSA pattern morphology on the trench width and on how the neutral brush covers the guiding pattern. We identify the relation between trench width and the emergence of defects with nanometer precision. Based on these studies, we develop a model that extends available free energy models by adding the effect of a non-zero defect density, which allows us to predict the patterning process window to achieve a low level of defects.
Authors : Katia Sparnacci (1), Michele Perego (2), Gabriele Seguini (2), Diego Antonioli (1), Valentina Gianotti (1), Michele Laus (1)
Affiliations : (1) Università del Piemonte Orientale ‘‘A. Avogadro’’, DISIT, Viale T. Michel 11, I-15121 Alessandria, Italy, INSTM UdR Alessandria; (2) Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, Italy
Resume : The capability to control dopant incorporation within semiconductor materials with atomic accuracy represents the major challenge toward further scaling down of electronic devices. In this work, we propose a new bottom-up technology for precisely controlling the amount of dopant atoms tethered on silicon substrates based on the self-assembly of dopant-containing end-functional polymers. Monodisperse polystyrene and poly(methyl methacrylate) polymers with different molar masses, end-terminated with a phosphate containing moiety were prepared and grafted to an activated silica surface by thermal annealing (T=250°C). Subsequent removal of the organic layer by oxygen plasma and capping with SiO2 leads to the formation of a P δ-layer embedded in a SiO2 matrix and spatially separated from the Si substrate. Taking advantage of the self-limiting nature of the “grafting to” process, precise control of the areal dose of dopants in the δ-layer from 3×10^13 to 8×10^13 atoms/cm^2 can be achieved by properly tuning the polymer molar mass. Moreover, repeated cycles of polymer grafting followed by plasma hashing led to a further stepwise increase in the dose of P atoms. P injection in the silicon substrate was promoted and precisely controlled by high temperature thermal treatments. Finally, the combination of this approach with block copolymer lithography is explored to control at the nanoscale the lateral confinement of the dopant atoms.
Authors : Cian Cummins1,2*, Graeme Cunningham1, Michael A. Morris1, Ryan Enright2*. E-mail: email@example.com, firstname.lastname@example.org
Affiliations : 1. AMBER@CRANN, Trinity College Dublin, Dublin, Ireland 2. Thermal Management Research Group, Efficient Energy Transfer (ηET) Dept., Nokia Bell Labs, Nokia Ireland, Blanchardstown Business & Technology Park, Snugborough Rd., Dublin 15, Ireland
Resume : The proliferation of advanced portable information and communication technology places substantial demands on current patterning techniques to satisfy future device and data needs. In this context, research on integrating high-performing nanomaterials such as 2D transition metal dichalcogenides (TMDs) with emerging bottom-up patterning methods is critical. In this talk, we will outline our approach for positioning exfoliated layered materials, e.g. MoS2, In2Te3, using PS-b-PxVP (x = 2 or 4) block copolymer templates with sub-10 nm resolution. Block copolymers offer a flexible, low-cost strategy to define nanotemplates over large surface areas1,2 and is a prime candidate for next-generation lithography. Our work assesses the precursor parameters including solution concentration, exposure period, and post-deposition treatment in forming well-defined nanofeatures. Directed self-assembly of few-layer TMDs is demonstrated revealing high-density coverage. We will also detail a more conventional deposition route using metal salt precursors3 to form GaTe, NbSe, and InTe binary nanowires. In summary, we present and discuss an innovative strategy to place inorganic nanomaterials at specific BCP sites that may find use to advance future information technologies owing to superior 2D TMD material properties. 1. M. A. Morris, Microelectronic Engineering 132, 207-217 (2015). 2. R. Lundy, S. P. Flynn, C. Cummins, S. M. Kelleher, M. N. Collins, E. Dalton, S. Daniels, M. A. Morris and R. Enright, Physical Chemistry Chemical Physics 19 (4), 2805-2815 (2017). 3. C. Cummins, T. Ghoshal, J. D. Holmes and M. A. Morris, Advanced Materials 28 (27), 5586-5618 (2016).
Poster Session : Francesc Perez-Murano
Authors : Hao Yang; Zhaogen Wang; Yong Wang
Affiliations : Membrane Science & Technology Research Center; State Key Laboratory of Materials-Oriented Chemical Engineering; Nanjing Tech University
Resume : Poly(ethylene oxide) (PEO) is well known for its excellent protein-repelling property. However, it remains challenging to fabricate membrane with uniform and robust coverage of PEO chains in a simple and efficient way. In this work, we fabricated composite membranes with mesoporous amphiphilic block copolymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO, abbreviated as SEO) as the size-selective layer and a macroporous membrane as the supporting layer. SEO solutions were coated on water-filled substrate membranes, and dried to obtain a dense SEO layer tightly coated on the substrate membranes. The SEO-coated substrates were then immersed in hot ethanol followed by air drying to cativate the SEO layers. Mesopores were generated in the SEO layer by a selective swelling-induced pore-formation process. The pore size in the SEO layer can be tuned simply by varying the swelling durations, which led to membranes with adjustable separation properties. Furthermore, the hydrophilic PEO blocks were selectively enriched on the pore walls in the SEO layer during the swelling process, rendering an intrinsically active surface on the membrane and making the composite membranes possess a superior antifouling property. The antifouling property of the composite membrane was investigated with bovine serum albumin (BSA) solution as the model foulant. The BSA flux decline rate of the membrane was as low as 4.1%, and the water flux recover ratio was up to 100% after multiple cycles of BSA filtration.
Authors : Xueqing Yang, Wei Chen, Tianying Sun, Yangyang Du, Haidong Bian, Zhenyu Zhang, Wenjun Zhang, Yangyang Li, Xianfeng Chen, Feng Wan
Affiliations : Department of Physics and Materials Science City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China.
Resume : N-doped graphitic carbon submicrorods were synthesized by thermal transformation of zeolite imidazolate framework-8 (ZIF-8) submicrorods. The morphology and pore structure of the carbon submicrorods were readily tuned by using tri-block co-polymer Pluronic F127 as a soft template. The as-synthesized carbon submicrorods with morphology preserved derived from submicrorods of ZIF-8 comprise both micro- and meso-pores with high surface areas of over 1000 m2 g-1. In addition, nitrogen-doping in the carbon submicrorods was achieved as was confirmed by XPS and EELS. The hybrid carbon submicrorods provide pseudo-capacitance that promotes electrochemical performance, rendering a high specific capacitance of up to 297 F g-1 at a current density of 0.5 A g-1 in a three-electrode system. A long cycle life was also demonstrated by recording a 90.26% preservation of capacitance after 104 cycles of charge-discharge at a current density of 4.0 A g-1. Furthermore, a symmetrical supercapacitor is fabricated by employing the carbon submicrorods, which shows good electrochemical performance with respect to energy, power and cycle life.
Authors : Lulu Wang, Haiying Huang*
Affiliations : State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
Resume : Nanotubes have attracted considerable attention due to their unique one-dimensional hollow structure, which are more efficient to capture, store and release nanomaterials. In this work, well-defined nanotubular micelles with uniform diameter and high aspect ratio were successfully prepared via self-assembly of a poly(styrene-b-4-vinyl pyridine-b-ethylene oxide) triblock terpolymer in binary solvent mixtures with assistance of solution thermal annealing. It was found that nanotubular micelles are formed by simultaneous unidirectional growth and solid-to-hollow transition with large solid cylindrical aggregates as precursors, which is distinct from conventional formation pathway. Moreover, the thermal annealing and cooling procedure allows for preparation of a series of novel kinetically frozen morphologies. By virtue of the radially compartmentalized structure, gold nanoparticles are able to be selectively incorporated into different micellar domains of the nanotubes, holding promise for fabrication of nanosensors and bioreactors. Acknowledgments: This work was supported by National Natural Science Foundation of China (Grant 21674112, 21474108).
Authors : Andrew Selkirk, Parvaneh Mokarian, Mick Morris
Affiliations : AMBER - CRANN, Trinity College Dublin, Dublin, Republic of Ireland
Resume : The self-assembly of large molecular weight block copolymers into spatially oriented nanodomains has opened up a range of new possibilities in the manufacture of sub-wavelength optical nanostructures, such as Si nanopillars for anti-reflective coatings (1). Devices have been synthesized thus far using high molecular weight PS-b-P2VP block copolymer on silicon substrates. This work expands this project, examining the formation of these domains on other substrate types - such as glass, Gorilla Glass (TM) and sapphire glass - and characterising feature sizes and optical performance. The synthesis process for nanostructures on amorphous substrates (e.g. glass) is more complex, as the interfacial chemistry varies greatly to Si. This requires the optimisation of parameters including polymer concentration, phase separation process, etch mask deposition, and etch recipes. Additionally, the ability of other large molecular weight BCPs to phase separate, specifically PS-b-PEO, is assessed, with the intention of gaining further insight into the mechanics of their phase-separation. PS-b-PEO has shown strong potential for nanostructure fabrication, however the domain sizes have remained below that required for optical applications in the visible spectrum (2). The fabrication parameters mentioned above are also optimised for large molecular weight PS-b-PEO, and the relative feature spacing, film coverage, diameters and nanostructure characteristics for both block copolymers are extensively compared. 1. Mokarian, P.; Senthamaraikannan, R.; Glynn, C.; Collins, T.; Cummins, C.; et al. Nano Letters 2017, 17, 2973-2978. 2. Cummins, C.; Ghoshal, T.; Holmes, J.; Morris, M.; Advanced Materials, 2016, 28, 5586-5618.
Authors : Xuan WANG, Florian AUBRIT, Fabienne TESTARD, Patrick GUENOUN, Ashod ARADIAN, Morten KILDEMO, Virginie PONSINET
Affiliations : CNRS, University of Bordeaux, CRPP UMR5031, 33600 Pessac, France ; CEA, CNRS, LIONS NIMBE UMR 3685, 91191 Gif sur Yvette Cedex, France ; Physics Department, NTNU, Trondheim 7491, Norway
Resume : Nanophotonics explores the possibility of modulating light propagation with very small amount of matter using nanoscale phenomena. The occurrence of plasmons at metal/dielectrics interfaces is one of the very relevant phenomena, which has encouraged, in the recent years, active research efforts towards the fabrication of nanostructured metal-dielectric materials and surfaces. This presentation will show how we used self-assembling block copolymers for the “bottom-up” formulation of original anisotropic plasmonic nanocomposites. In particular, we produce and study periodic cylindrical and lamellar assemblies composed of nanometric domains of pure polymer and domains of composite of polymer loaded with a high density of gold nanoparticles. The spectral variation of their anisotropic effective dielectric permittivity is determined by spectroscopic ellipsometry using appropriate effective medium models. For large gold loading, the lamellar stacks present a frequency domain, in which the ordinary and extraordinary components of the dielectric function are of opposite signs. This peculiar property, called “hyperbolic”, allows for the propagation of large magnitude wavevectors, carrying details finer than half the wavelength, otherwise corresponding to evanescent non-propagative waves in a usual dielectric.
Authors : Hyungju Ahn, Sang-sul Lee, Du Yeol Ryu
Affiliations : Pohang Accelerator Laboratory; Pohang Accelerator Laboratory; Yonsei University
Resume : Arrays of nanopores have widely been used as templates for high-surface area applications, like high-density storage media, catalysis, and ultrafiltration (UF) membranes. Block copolymers (BCPs) can be used as nanopore-generating materials to produce templates and scaffolds for the fabrication of nanostructured materials, since one component can be selectively removed by chemical treatment. Especially, for UF membrane applications, the self-assembly of BCP present an attractive approach for highly size-selective, permeable membranes due to their narrow size distributions and high pore densities. Here, nanoporous ultrafiltration membranes were obtained by the self-assembly of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) where, cylindrical microdomains were oriented normal to the substrate and air interfaces, and in the interior of the films, the microdomains were randomly oriented. Continuous nanopores that penetrated through the film were readily produced by a simple preferential swelling of the PMMA microdomains. The confined swelling and rapid contraction of PMMA microdomains generated well-defined uniform pores with diameters to 17.5 nm. The size selectivity and rejection of Au nanoparticles (NPs) for these ultrafiltration (UF) membranes were demonstrated, suggesting an efficient route to tunable, noncomponent-degradative UF membranes.
Authors : Hong Kyoon Choi1, Jae-Byum Chang2, Caroline Ross3
Affiliations : 1 Division of Advanced Materials Engineering, Kongju National University, Cheonan, Republic of Korea 2 Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea 3 Department of Materials Science and Engineering, Massachusetts Institute of Technology, U.S.A.
Resume : BCPs self-assemble within curved templates has been a question of long-standing interest. BCPs or BCP blends with lamellar or cylindrical microdomains have been templated within 3D spherical or cylindrical pores, leading to a range of microdomain geometries including concentric cylinders or vesicles, stacked tori or disks, helices, or pea-pod structures. Helical structures have also been reported in chiral block copolymers, triblock terpolymers, terpolymer micelles, and BCP globules. There have been reports of concentric ring formation in BCP films confined in circular templates, and from half-onion structures formed in hemispheres, which have applications in the fabrication of sensors based on surface-enhanced Raman scattering. BCPs assembling on a spherical surface are predicted to form spiral structures, and we reported a spiral made from a cylindrical microdomain formed within a hexagonal template. However, there has been little work on the control of the chirality of helical structures or spirals using BCP self-assembly. In this study, we demonstrate that confinement of a cylindrical-morphology BCP in a shallow circular pit can produce either concentric rings or a spiral. A spiral is promoted by the presence of a notch-shaped feature within the template which controls the spiral chirality. The length of the spiral increases with the diameter of the template. Design of the notch geometry enabled double spirals to be formed. A notch of width ≈ L0 promotes spirals even for commensurate pit sizes indicating the critical importance of the inner shape of the template. For smaller notches, spirals formed for incommensurate template diameters and rings for commensurate template diameters. Analogous to using a notch to initiate a spiral in a circular pit, our approach could be extended to guide the chirality of 3D helical spirals formed in cylindrical confinements with a helical ramp template. 2D and 3D chiral nanostructures have a range of potential applications in the sensing of molecular chirality or as chiral metameterials. Chiral nanostructures have so far only been fabricated by top-down lithography or self-assembly of nanoparticles interacted with chiral molecules, and this study provides an effective alternative route to fabricate chiral nanostructures via directed self-assembly.
Authors : Aynur Guliyeva, Marylène Vayer, Christophe Sinturel, Fabienne Warmont, Marie-Pierre Faugere, Pascal Andreazza, Atsushi Takano and Yushu Matsushita
Affiliations : Interfaces, Confinement, Matériaux et Nanostructures (ICMN) UMR 7374-CNRS-Université d’Orléans, CS 40059, 45071 Orléans cedex 2, France Laboratory of Physical Chemistry of Polymers, Department of Molecular & Macromolecular Chemistry, Nagoya Univesity, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
Resume : In thin films of block polymers composed of more than two blocks, the accurate selective identification of each domain in the film is of prime importance for a clear assignation of the morphologies. We will focus this presentation on the selective identification of poly(isoprene) (PI), poly(vinylpyridine) (PVP), and poly(styrene) (PS) domains in various systems of PI-b-PS-b-PVP (including blends). For this purpose, we have combined AFM, TEM and GISAXS analyses coupled to specific modifications, in order to specifically identify each phases. AFM characterization was performed thanks to a selective elimination of PI by ozonolysis and selective revelation of P2VP by swelling in ethanol. For TEM, thin films were removed from the Si/SiO2 substrate by floatation at the surface of a NaOH solution, carefully collected onto a grid and selectively stained by heavy metals. For GISAXS characterization, we developed an unusual methodology to overcome the weak electronic density contrast in the sample, based on the selective staining of P2VP by I2 or elimination of PI by ozonolysis. The combination of these methods will be exemplified on selected morphologies with gradual complexities.
Authors : Jongseol Jeon, Inhye Kim, Seon-mi Jin, Jinwoo Nam, Kwonhyeok Yoon, Kang Moo Huh, Eunji Lee
Affiliations : Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea; Department of Polymer Science and Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
Resume : Generating the hierarchical nanostructures from various polymers to self-assembled aggregates and discovering the assembling process are important not only to discover the new characteristics of functional nanomaterials but also to improve their physical and chemical properties. Herein, we have fabricated the unique nanostructures including pupa-like and caterpillar-like structures formed by emulsification-induced self-assembly of biocompatible, semicrystalline poly(ε-caprolactone)-block-poly(ethylene oxide) (PCL-b-PEO). The growth mechanism from pupa-like to caterpillar-like structures was confirmed by transmission electron microscopy. It is observed that pupa-like structure was kinetically trapped morphology before being caterpillar-like structure. The caterpillar-like structure with microscale length was generated by end-to-end coupling of short elemental nanostructures to avoid the exposed PCL segment and water. The crystallinity of PCL increased as a function of molecular weight of PCL block, resulting in a driving force for the formation of orthogonal nanostructures. This sophisticated approach would provide a novel nanoplatform for applying the semicrystalline polymer.
Authors : Cindy Gomes Correia (1), Karim Aissou (1), Muhammad Mumtaz (1), Gilles Pécastaings (1), Xavier Chevalier (2), Georges Hadziioannou (1), Christophe Navarro (2), Guillaume Fleury (1)
Affiliations : (1) Centre National de la Recherche Scientifique, Laboratoire de Chimie des Polymères Organiques, UMR 5629, IPB/ENSCBP, Allée Geoffroy Saint Hilaire, Bât B8, F-33615, Pessac Cedex, France and Université de Bordeaux, Laboratoire de Chimie des Polymères Organiques, UMR 5629, IPB/ENSCBP, Allée Geoffroy Saint Hilaire, Bât B8, F-33615, Pessac Cedex, France; (2) Arkema - Groupement de recherches de Lacq, RN117, BP 34, 64170 Lacq Cedex France;
Resume : Polycarbosilane-based block copolymers have been designed and evaluated for directed self-assembly applications thanks to their propensity to form well-defined structures of high resolution[1,2]. Following these works, we have studied these materials (both poly(1,1-dimethyl silacyclobutane)?b- poly(styrene) (PDMSB-b-PS) and poly(1,1-dimethyl silacyclobutane)?b-poly(methyl methacrylate) (PDMSB-b-PMMA)) as a platform of morphologies for potential nanotechnological applications. Using industrially-friendly processes, lamellar, cylindrical, spherical and gyroid phases were obtained with sub-20 critical dimension in thin films. We highlight the parameters allowing the control of both the self-assembly and the structure orientation in thin films through the influence of self-assembly kinetics, surface energy and film thickness. Additionally, we show how the commensurability between the gyroid lattice and the film thickness leads to the different plans of the gyroid phase including the (211) G one with a 18.2 nm pitch. 1. Aissou, K.; Mumtaz, M.; Fleury, G.; Portale, G.; Navarro, C.; Cloutet, E.; Brochon, C.; et al. Adv. Mater. 2015, 27, 261?265. 2. Fleury, G.; Aissou, K.; Mumtaz, M.; Chevalier, X.; Nicolet, C.; Navarro, C.; Fernandez-Regulez, M; et al. Proc. SPIE 9425, Advances in Patterning Materials and Processes XXXII. 2015; 94250Z. 3. Aissou, K.; Mumtaz, M.; Portale, G.; Brochon, C.; Cloutet, E.; Fleury, G.; Hadziioannou, G. Small 2017, 13, 1603777.
Authors : Joachim Zajadacz*, Klaus Zimmer*, Andre Mayer**, Christian Steinberg**, Hella-Christin Scheer**
Affiliations : * Leibniz Institute of Surface Engineering, Permoserstr. 15, D-04318 Leipzig, Germany ** Department of Electrical and Information Engineering, University of Wuppertal, Rainer-Gruenter-Str. 21, D-42119 Wuppertal, Germany
Resume : Self-assembled vertical-aligned lamellar DiBCP patterns, however, enable a straightforward approach for pattern transfer into the functional material by standard technologies for nanopatterned functional surfaces. The current work focuses on the short-time high-temperature annealing of DiBCPs forming self-assembled lamellar patterns. There are at least two ways to reduce the time for pattern formation: solvent annealing and high temperature annealing. The short time high temperature annealing was investigated in the temperature range from 260 to 300° C and for annealing times between 3 s to 15 min. Within this experimental range a clear phase separation, but with different fidelity, for all temperature- time combinations was observed. SEM images show well-ordered DiBCP films with perpendicular oriented lamellar structures. The best ordering of the lamellar structures were observed at an annealing temperature of 280 °C; higher temperature may cause degradation effects. At a fixed annealing temperature of 280 °C a time series down to 3 s shows gradual reduction of the long range order. Less perfect lamellar ordering is observed for all annealing times.
Authors : Mohamed Loucif Seiad, Roel Gronheid, Marhoun Ferhat,
Affiliations : Imec, Kapeldreef 75, B-3001 Leuven, Belgium. Semiconductor and Functional materials laboratory, University Amar Telidji of Laghouat BP 37G, Ghardaïa Road, 03000 Laghouat, Algeria. KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh, Saudi Arabia, Centre de Développement des Technologies Avancées, DMN, BP N°17 Baba Hassen, 16303 Algiers, Algeria. Department of Physics, the University of the West Indies, Mona Campus, Kingston 7, Jamaica.
Resume : In the present work, we used the design of experiment (DOE) to investigate the effect of the process parameters on the self-assembly (S-A) of cylinder forming of poly (styrene-b-Methyl-Methacrylate) (PS-b-PMMA), such as the annealing temperature (T), time (t) and the film thickness (ft). Focusing on the holes defect ratio and the grain boundaries. The Fingerprint Contact Roughness (FCR) metrology was used to analyze the SEM images, collected at each process step. Treatment of experimental data was performed by using Plackett-Burman design. The Pareto chart of effects shows that the most important factor in the block copolymer S-A process is the annealing time (8.9). The annealing temperature has also a positive effect but at lower level (4.9). Otherwise, (ft) has the least effect on the response (2.5). The man effects plot indicates that for both (t and T) the level of influence is higher. This means that, longer annealing time lead to better rearrangement of cylinders into hexagonal phase. However the influence level of (ft) is quite limited in this study. The ANOVA results confirm that all the factors exhibit p-values less than (0.05) indicating that they are significantly different from zero, at 93.16% confident level when the parameters change from level (-1) to level (1). Finally, the DOE allows a mathematical representation of the responses according to all factors. The regression is represented by polynomial equations corresponding to the coded and uncoded parameters.
Authors : Géraldine Layrac 1, Simon Harrisson 2, Mathias Destarac 2 , Corine Gérardin 1 and Didier Tichit 1
Affiliations : 1 Equipe “ Matériaux Avancés pour la Catalyse et la Santé “, Institut Charles Gerhardt UMR 5253, Montpellier, France. email@example.com; 2 Equipe “ Polymères de Précision par Procédés Radicalaires ”, Laboratoire IMRCP UMR 5623, Toulouse, France.
Resume : We propose a direct and fully colloidal route for the preparation of aqueous suspensions of highly stable and poorly aggregated layered double hydroxide (LDH) nanoparticles using hybrid polyion complex micelles (HPIC). HPIC micelles are obtained by complexation between metallic cations and the complexing block of asymmetric poly(acrylic acid)-b-poly(acrylamide) a or poly(vinylphosphonic acid)-b-poly(acrylamide) b (PAA-b-PAm or PVPA-b-PAm) double hydrophilic block copolymers (DHBC). We showed that the LDH colloids are obtained in two steps from mixed solutions of M2+ and Al3+ cations, and DHBC: i) first formation of HPIC micelles constituted almost entirely of Al3+ due to the preferential complexation of the trivalent cations, while the divalent cations remain free in solution; ii) transformation of the DHBC/Al3+ HPIC micelles into DHBC/aluminum hydroxide colloids upon hydroxylation with NaOH. Then the partial dissolution of DHBC/aluminum hydroxide and the progressive incorporation of M2+ ions leads to the precipitation of the LDH phase in the colloid. The formation mechanism depends on the M2+ speciation, e. g. the Cu2+/Al3+ couple is hydroxylated at lower pH than the Mg2+/Al3+ couple and the properties of HPIC micelles depend on the nature of the DHBC complexing block. Indeed Mg and Al yields in the HPIC micelles are higher upon complexation with PVPA than with PAA block of the DHBC. The complexation degree (R) (R = AA or VPA/(Mg + Al)) is a major parameter controlling the colloidal stability of the LDH suspension. It also controlled the hydrodynamic diameter of the DHBC/LDH colloids,, which decreased from 530 nm down to 60 nm, and the growth of the LDH phase with a mean size of the individual particles in the range 50-20 nm when R increased. XRD and TEM results show that the LDH particles are preferentially intercalated by the negatively charged PAA block of the DHBC rather than by chloride anions of the initial salts when R increases. Moreover, the stability of the colloids depends on the asymmetry degree between the anionic block and the acrylamide block and also on the architecture of the DHBC. This colloidal route appears promising for the developpement of biofunctional hybrid nanovectors and for basic catalysis applications. a. Géraldine Layrac, Mathias Destarac, Corine Gérardin and Didier Tichit, Highly Stable Layered Double Hydroxide Colloids: A Direct Aqueous Synthesis Route from Hybrid Polyion Complex Micelles., Langmuir 2014, 30, 9663. b. Géraldine Layrac, Corine Gérardin, Didier Tichit, Simon Harrisson and Mathias Destarac ,Hybrid polyion complex micelles from poly(vinylphosphonic acid)-based double hydrophilic block copolymers and divalent transition metal ions., Polymer, 2015, 72, 292-300
Authors : Marta Fernández-Regúlez, Laura Evangelio, Christian Pinto-Gómez, Steven Gottlieb, Joan Bausells and Francesc Perez-Murano
Affiliations : Instituto de Microelectrónica de Barcelona (IMB-CNM CSIC), Campus UAB 08193, Bellaterra, Barcelona (Spain)
Resume : Directed self-assembly (DSA) of block copolymers (BCPs) is a promising alternative to advance in miniaturization for the semiconductor industry due to its high resolution and process simplification compared with other approaches. In particular, line and space using lamellar BCPs can be used for the definition of nanowire-based devices. However, when BCP materials of very low dimension are used, a high-resolution lithography (such as e-beam or extreme UV) is required for the definition of the guiding pattern, which limits the opportunities for its applicability. In this communication, we propose the fabrication of nanowire-based devices by the combination of conventional optical lithography and DSA of BCPs. The guiding patterns for DSA and contacting lines and pads are defined in a single step by optical lithography. Then, a lamellar PS-b-PMMA block copolymer is aligned perpendicularly to the walls of the topographical guiding patterns. Finally, BCP features are transformed into functional nanowires using two different approaches. In the first approach, PMMA block is selectively removed and PS block is used as an etch mask for the transfer into the silicon under-layer. In the second approach, an organic/inorganic nanocomposite is formed through the selective incorporation of a metal oxide into the PMMA block by means of sequential infiltration synthesis. After the removal of PS, free-standing metal-oxide nanowires are formed.
Authors : Katia Sparnacci (1), Michele Perego (2), Gabriele Seguini (2), Diego Antonioli (1), Valentina Gianotti (1), Riccardo Chiarcos (1), Michele Laus (1)
Affiliations : (1) Università del Piemonte Orientale ‘‘A. Avogadro’’, DISIT, Viale T. Michel 11, I-15121 Alessandria, Italy; (2) Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, Italy
Resume : The aim of this work is to obtain block copolymer brushes by a combined grafting to and grafting from approach. A new strategy was employed in which the second block re-growths starting from a homopolymer brush layer obtained by the grafting to approach. In detail, several polystyrene samples with molecular weight ranging from 2.5 to 13 kg/mol and narrow molar mass distribution were synthesized by nitroxide-mediated-polymerization (NMP) using N-tert-butyl-N-[1-diethylphosphono(2,2-dimetylpropyl)] nitroxide (SG1/DEPN) as polymerization controller. Such polymers were grafted onto a silicon oxide surface by Rapid Thermal Processing (RTP) at different temperatures. As thermolabile groups deriving from the terminal SG1 are located to the silica surface, they could allow a synthesis of block copolymers via the grafting from approach by surface initiated NMP. Preliminary experiments of regrowth from surface were conducted with deuterated styrene and 4-vinylpyridine. The corresponding block copolymer brushes were obtained and their characteristics discussed as a function of the relevant reaction parameter.
Authors : Katia Sparnacci (1), Michele Perego (2), Gabriele Seguini (2), Cristiano Aliberti (1), Diego Antonioli (1), Valentina Gianotti (1), Michele Laus (1)
Affiliations : (1) Università del Piemonte Orientale ‘‘A. Avogadro’’, DISIT, Viale T. Michel 11, I-15121 Alessandria, Italy; (2) Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, Italy
Resume : Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesized for p-type doping of silicon substrates through spin-on technique. Several polymers were prepared using the ARGET-ATRP method using tert-butyl 2-bromoisobutyrate as initiator, changing monomer to initiator ratio and the reaction time. After polymerization, polystyrene samples were functionalized in order to end-cap the chains with a boron-containing molecule. Various polymers were characterized by SEC, to estimate Mn, Mw and PDI, by NMR (1H and 13C) in order to investigate the correct structure of the molecules and by TGA-GC-MS for knowing the thermal behavior and the amount of boron into the polymers.
Authors : K. Brassat, D. Kool, A. Taube, M. Schaper, J. K. N. Lindner
Affiliations : Nanostructuring, Nanoanalysis and Photonic Materials group, Dept. of Physics, Paderborn University, Paderborn, Germany; Center for Optoelectronics and Photonics Paderborn CeOPP, Paderborn, Germany; Dept. of Mechanical Engineering, Paderborn University, Paderborn, Germany
Resume : Block copolymer (BCP) lithography for self-assembled thin film nanopatterning is known to strongly depend on the interactions between the polymer species of the BCP and the substrate surface. The system of PS-b-PMMA on SiO2 surfaces is investigated by many groups, as one of the most promising applications of BCP lithography lies in semiconductor technology. A silicon oxide surface can, however, only be patterned by BCP lithography if the surface is neutralized, e.g. by a RCP brush, which then allows for pattern orientation control. For many other applications of BCP lithography materials other than SiO2 are of interest. In particular, nanopatterned TiO2 on Ti-6Al-4V alloys can be exploited in biomedicine. Here, we present BCP lithography on different surfaces: smooth and rough Au and Pt are investigated as well as (3D-printed) Ti-6Al-4V (alpha and beta) alloy surfaces. It will be shown that - depending on the polar fraction of surface energy - active surface neutralization is not necessary to obtain ordered arrays of nanopores. An additional influence of surface roughness is analyzed in detail based on automated evaluation of nanopore diameters and shape. The morphology of the BCP PS-b-PMMA on the different material surfaces is investigated by top view SEM, SEM of the BCP thin film backside after its release from the surface and cross-sectional (analytical) TEM.
Authors : S. Gottlieb (1), Y. K. Ryu (2), M. Lorenzoni (1), L. Evangelio (1), M. Fernández-Regúlez (1), C. Rawlings (3), M. Spieser (3), A.W. Knoll (2), F. Perez-Murano (1)
Affiliations : 1: Instituto de Microelectrónica de Barcelona IMB-CNM, CSIC, 08193 Bellaterra, Barcelona, Spain; 2: IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland; 3: SwissLitho AG, Technoparkstrasse 1, 8005 Zürich, Switzerland;
Resume : The measurement of thermal transport on the nanoscale is challenging, and of great importance for many fields of research, such as device and energy technology. Understanding the thermal properties of block copolymers is an inherently interesting question, as block copolymers are used as templates for nano-lithographical processes. Moreover, their controlled nanoscale feature sizes provide a good metrology standard for testing the resolution potential of an imaging method. We present a probe-based thermal imaging technique capable of providing sub-10 nm resolution. We demonstrate this resolution by resolving microphase separated PS-b-PMMA block copolymers with molecular weights ranging from 42 kg/mol to 79 kg/mol, which result in half-pitch widths between 11 nm and 19 nm. At each pixel location, the jump in and out of contact is monitored by recording an entire approach-retract cycle. Electrostatic actuation is used and provides pixel times of ~5 ms and therefore relatively fast scanning speeds. The excellent lateral resolution of the presented technique is enabled by the use of resistively heated tips with apex radii of < 5 nm. We are capable of detecting a heat transport into the sample surface of a few μW. The difference in detected heat transfer between the PS domain and the PMMA domain is in the range of 25 % and therefore in-line with literature values. The presented technique represents a novel way to image complex mixed polymeric systems with high resolution and a good material contrast based on the differences in the material’s thermal conductivity.
Authors : S. Gottlieb (1), B. Rösner (2), L. Evangelio (1), M. Fernández-Regúlez (1), A. Nogales (3), M.C. García-Gutiérrez (3), T.F. Keller (4), T.A. Ezquerra (3), C. David (2), F. Perez-Murano (1)
Affiliations : 1: Instituto de Microelectrónica de Barcelona IMB-CNM, CSIC, 08193 Bellaterra, Barcelona, Spain; 2: Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland; 3: Instituto de Estructura de la Materia, IEM-CSIC, 28006 Madrid, Spain; 4: Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg, Germany
Resume : In block copolymer lithography, lithographically defined guiding patterns can be used to induce long-range order in a thin film of block copolymers. We study the directed self-assembly of an 11 nm half-pitch PS-b-PMMA block copolymer in topographical guiding patterns that consist of arrays of silicon oxide lines of sub-10 nm width. The lines have been fabricated by electron-beam lithography using hydrogen silsesquioxane (HSQ) as the resist layer. Detailed analysis of the structures by atomic force microscopy (AFM), scanning electron microscopy (SEM) and grazing incidence small angle X-ray scattering (GISAXS) reveals a self-assembly morphology with long-range order. Unlike it is usually the case in graphoepitaxy, the block copolymer surrounds the guiding pattern features, e.g. block copolymers are deposited not only between the features, but also on top of them. We discuss the implications of this self-assembly mode for a successful guiding pattern design and compare the resulting guiding pattern design rules with those known for topographic guiding patterns with lateral dimensions significantly above 10 nm.
Authors : E. Cianci (1), D. Nazzari (1,2), G. Seguini (1), F.E. Caligiore (1,3), M. Perego (1), K. Sparnacci (4), V. Gianotti (4), M. Laus (4)
Affiliations : (1) IMM-CNR, Agrate Brianza Unit, via C. Olivetti 2, 20864 Agrate Brianza (MB), Italy; (2) Department of Physics, Università Statale di Milano, Via G. Celoria 16, 20133, Milano (Mi), Italy; (3) Department of Material Science, Università di Milano Bicocca, Via R. Cozzi 53, 20125 Milano, Italy; (4) Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria, Italy
Resume : Selective growth of inorganic materials in one of the domains of block?copolymer (BCP) thin films can be used for enhancing polymer etch resistance for pattern transfer to the substrate. Selective sequential infiltration synthesis (SIS) of self-assembled PS-b-PMMA thin films has been proposed to convert PMMA nanostructures in inorganic Al2O3 using trimethylaluminum (TMA) in combination with H2O as precursors. Perpendicular orientation of the nanodomains with respect to the substrate in PS-b-PMMA films requires the introduction of a grafted random copolymer (RCP) film with tailored composition to neutralize the preferential wettability of PS with respect to the PMMA on the SiO2 surface. However, the RCP film contains MMA monomeric units and consequently is infiltrated during SIS process, with the formation of an Al2O3 continuous layer at the interface between the BCP film and the substrate. A breakthrough process with a specific dry etching chemistry is required to remove this layer and expose the Si substrate. Therefore, detailed knowledge of the infiltration process in this RCP layer is mandatory for the effective exploitation of the infiltrated Al2O3 nanostructures as hard mask for lithographic applications. In this work, we present a detailed investigation of the infiltration of Al2O3 in P(S-r-MMA) thin films with thickness ranging from 8 to 100 nm and variable styrene content ranging from 0 to 100% by means of in situ and ex-situ analysis.
Authors : Tommaso J. Giammaria (1,2), Gabriele Seguini (1), Michele Perego (1), Christopher K. Ober (3), Katia Sparnacci (2), Diego Antonioli (2), Valentina Gianotti (2), Michele Laus (2)
Affiliations : (1) Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, 20846 Agrate Brianza (MB), Italy (2) Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Viale T. Michel 11, Università del Piemonte Orientale A. Avogadro, INSTM, Alessandria 15121, Italy (3) Department of Materials Science and Engineering, Cornell University, Bard Hall, Ithaca, NY 14853, USA
Resume : Block copolymer (BCP) self-assembly (SA) leading to thin films with periodic ordered nanostructures featuring different morphologies has been exploited in a number of technological applications. Among them, polydimethylsiloxane (PDMS) containing BCPs have attracted a great interest because of the possibility to generate high-resolution nanostructures with dimension below 10 nm. The SA of the PDMS-containing BCPs in periodic nanostructures can be achieved by different approaches, but thermal annealing would be highly desirable for easy integration in a product process flow. In this work, we report a systematic study on the SA kinetic and morphological evolution of a cylinder-forming polystyrene-block-poly(dimethylsiloxane-random-vinylmethylsiloxane) PS-b-P(DMS-r-VMS) thin film (Mn = 22 kg/mol). BCP films were deposited on PS or PMMA brushes by spin casting from various solvents. A simple thermal treatment at high temperature was used to promote the formation of PDMS cylinders embedded in a PS matrix and parallel oriented with respect to the substrate. Grain coarsening kinetic of the system was studied considering the time evolution of correlation lenght (?). In most of the cases a power law dependence of ? ~ t^? with ? = 0.21 was obtained irrespective of the combination of brush layer and solvent. For some specific combinations, conversion from parallel cylinders to dots was observed highlighting the important role of residual solvent on the SA process.
Authors : Barry Reid (1), Alaric Taylor (1), Benjamin Schmidt-Hansberg (2) and Stefan Guldin (1)*
Affiliations : (1) Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K. (2) Chemical & Process Engineering, Coating & Film Processing, BASF SE, Carl-Bosch-Strasse 38, Ludwigshafen am Rhein 67056, Germany
Resume : Mesoporous inorganic thin films represent a field of research with growing importance in applications such as sensing, optics, photovoltaic cells and protective coatings. Block copolymers (BCPs) are ideal candidates in the structure-directed assembly of mesoporous inorganic materials. When combined with well-established inorganic sol-gel chemistry methods, BCPs enable solution-processing of mesoporous inorganic architectures with controlled porosity, pore sizes and pore arrangement for a broad materials library. One aspect that hampers the application of porous coatings is their relatively poor mechanical stability and scratch resistance. During this work, we investigate factors that influence the mechanical properties of block copolymer-derived mesoporous aluminosilicate network and identify material strategies to promote their long-term stability. Key parameters such as the porosity, pore size, aluminosilicate content and sol additives are systematically varied and the resulting coatings characterised by a combination of pencil scratch tests, profilometry, spectroscopic ellipsometry, ellipsometric porosimetry and atomic force microscopy.
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Block-Copolymer Morphologies - I : Pawel Majewsky
Authors : Jin Kon Kim
Affiliations : Pohang University of Science and Technology
Resume : The microdomains obtained by block copolymer (BCP) self-assembly are mainly decided by the volume fraction of one block. For instance, the lamellar microdomains are expected for symmetric volume fractions, whereas spherical microdomains are obtained for highly asymmetric volume fraction. However, it is very difficult to fabricate highly asymmetric line patterns based on BCP. We successfully obtained highly asymmetric lamellar morphologies by the use of binary blends of block copolymers [polystyrene-b-poly(2-vinyl pyridine) copolymer (PS-b-P2VP) and PS-b-poly(4-hydroxystyrene) copolymer (PS-b-PHS)] where P2VP and PHS are capable of the hydrogen bonding. We obtained the asymmetric lamellar microdomains having lamellar width ratio of 4:1. This ratio was even increased up to 6:1 with increasing the degree of hydrogen bonding. Finally, we obtained core-shell double gyroids at highly asymmetric volume fractions by blending of polyisoprene-b-polystyrene-b-poly(2-vinylpyridine) (ISP) triblock terpolymer and polyisoprene-b-polystyrene (IS) diblock copolymer. At overall volume fractions of PI (0.12), PS (0.79), and P2VP (0.09), PI consists of thin core and PS forms thick shell, while P2VP becomes thin matrix.
Authors : Daniel F. Sunday1, Alice B. Chang2, Christopher D. Liman1, Eliot Gann1, Dean M. Delongchamp1, Mark W. Matsen3, Robert H. Grubbs2, Christopher L. Soles1,
Affiliations : 1. National Institute of Standards and Technology, Gaithersburg, MD 20899, United States 2. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States 3. Department of Chemical Engineering, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
Resume : Bottlebrush polymers are an intriguing class of materials, with unique properties due to their ability to reach large molecular weights without becoming entangled. Bottlebrush block copolymers (BCPs) are the natural extension of the homopolymer brushes, and systems with lamellar morphology have both larger scaling exponents compared to linear BCPs and higher mobility, enabling fast assembly of lamellae with large pitches. In one example, PLA-b-PS-b-PEO bottlebrushes exhibited unusual scaling behavior where an increase in the PEO backbone length resulted in a decrease in the pitch for BCP lamellae. Using soft X-ray reflectivity and near edge absorption fine structure spectroscopy (NEXAFS) measurements we evaluate how each component is distributed throughout the lamellae to determine the origin of this scaling. The presence of the midblock, PS, at the top surface of lamellae oriented parallel to a substrate is confirmed by both techniques and demonstrates that even for densely grafted bottlebrushes the formation of loops, analogous to linear triblocks, is possible. Self-consistent theory calculations match the experimentally determined component distributions and calculated backbone concentrations from self-consistent field theory also provide evidence of backbone flexibility.
Authors : Morgan Stefik
Affiliations : University of South Carolina, Department of Chemistry and Biochemistry Director of South Carolina SAXS Collaborative
Resume : Block copolymers hold tremendous promise for the realization of tailored porous nanomaterials. Such tailored structures are ideal for the study of and optimization of diverse technologies. Demonstrations to date, however, have broadly struggled to deliver architectures with independent control over the pore and wall dimensions. This historic limitation is partially due to the popular use of dynamic self-assembly processes that are subject to the “tyranny of the equilibrium.” I will present an emerging approach based rather upon kinetic-controlled of block copolymer micelles as a new nanofabrication tool kit. Kinetic control is historically difficult to reproduce, a challenge that is now resolved with switchable micelle entrapment to yield reproducible and homogeneous nanomaterial series that follow model predictions. This approach enables seamless access from meso-to-macroporous materials with unprecedented ~2 Å precision of feature size tuning, commensurate with the underlying atomic dimensions. The development of new kinetic-controlled block copolymer processes opens new opportunities to realize novel strategies for nanoscale control.
Block-Copolymer Morphologies - II : Jin Kon Kim
Authors : Pawel W. Majewski, Arkadiusz Leniart, Andrzej Sitkiewicz, Young-Woo Chu, Chinedum Osuji, Atikur Rahman, Masafumi Fukuto, Gregory Doerk, Kevin Yager, Charles Black
Affiliations : Chemistry Department, University of Warsaw, Poland Chemical and Environmental Engineering, Yale University, New Haven, USA Indian Institute of Science Education and Research, Pune, India Center for Functional Nanomaterials, Brookhaven National Laboratory, NY, USA
Resume : Block copolymers (BCPs) thin films offer a promising way for creating nanostructured periodic patterns on various substrates. Ordered BCP patterns are frequently utilized as etching or deposition masks or as synthetic templates in fabrication of various functional inorganic nanomaterials. Unfortunately, the range of periodic morphologies offered by typical diblock copolymer thin films is rather limited and does not meet the need for more refined structures required in many applications, e.g., layered architectures common in electronics. Without resorting to more complex system such as multi-block copolymers or liquid-crystalline BCPs, the two most commonly used motifs in diblock systems are single layer patterns composed of periodic “lines” (with rectangular or circular cross-section) and hexagonally-packed “dots” (spheres, half-domes or short rods). In my talk, I will present two strategies of directed self-assembly of BCP multilayers, where non-conventional structural motifs are produced either in a step-by-step process of stacking and metallization of laser-ordered BCP films  or by immobilization of the bottom layers of the stack with an oxide-precursor crosslinker, followed by the conversion to the inorganic replica in a single ashing step . Finally, I will discuss an approach called self-assembly pathway engineering, which utilizes a rational sequence of two directing biases to steer the evolution of BCP morphology into the desired spatial state – an array of single-domain hexagonally-packed vertical cylinders.  P. W. Majewski, A. Rahman, C. T. Black, K. G. Yager, Arbitrary Lattice Symmetries via Block Copolymer Nanomeshes. Nature Communications ,2015, 6  A. Rahman, P. W. Majewski, G.Doerk, K. G Yager, C. T. Black. Non-native three-dimensional block copolymers. Nature Communications 2016, 7, 13988  Y. Choo, P. W. Majewski, M. Fukuto, C. O. Osuji, K. G. Yager. Pathway-engineering for highly-aligned block copolymer arrays. Nanoscale 2018, Advance Article
Authors : Tamar Segal-Peretz
Affiliations : Technion- Israel Institute of Technology
Resume : Block copolymer (BCP) self-assembly is a versatile and scalable method for ordered nanoscale structures fabrication. In recent years, both self-assembly and directed self-assembly (DSA), where lithographically defined pre-patterns directed the BCP into highly aligned morphologies, have received much attention due to their potential in nano-manufacturing, optical coatings and membrane applications. While BCP films and particles are inherently three-dimensional (3D), understanding their 3D structure and exploiting it is still lacking. Here we combine scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning TEM (STEM) tomography to study the 3D structure of self-assembled BCP films, DSA films, and BCP particles. We harness sequential infiltration synthesis (SIS), a method that enables growth of metal oxides selectively within the polar domains of BCP, to create high imaging contrast for STEM characterization and tomography. 3D probing of lamellar and cylindrical BCP films revealed the through-film morphology, changes in feature’s roughness with depth, and defects that were previously hidden underneath the surface. Furthermore, by exposing the SIS-treated BCP to oxygen plasma, BCP-templated Al2O3 nanostructures were fabricated and the relationship between the BCP morphology, the SIS growth, and the resulting inorganic nanostructures was studied. We show that by understanding the diffusion of SIS precursor in the BCP film, it is possible to control the metal oxide growth through the depth of the film, adding another degree of freedom to BCP-based 3D nanostructures.
Authors : Aynur Guliyeva, Marylène Vayer, Christophe Sinturel, Fabienne Warmont, Marie-Pierre Faugere, Pascal Andreazza, Atsushi Takano and Yushu Matsushita
Affiliations : Interfaces, Confinement, Matériaux et Nanostructures (ICMN) UMR 7374-CNRS-Université d’Orléans, CS 40059, 45071 Orléans cedex 2, France ; Laboratory of Physical Chemistry of Polymers, Department of Molecular & Macromolecular Chemistry, Nagoya Univesity, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
Resume : Self-organization of block copolymers allows to form nanopatterns which have attracted a considerable attention as an alternative approach to overcome the characteristic size limitation of the conventional lithography processes. When linear triblocks are used in combination with other block polymers, they can lead to peculiar organization as demonstrated by Matsushita’s group. For example, it has been demonstrated that blends of 2 linear triblock polymers poly(isoprene)-block-poly(styrene)-poly(2-vinylpiridine) leads to an ordered array of rectangular-shaped cylinders with 4-fold symmetry in bulk, which could be very interesting for surface nanopatterning if prepared in the form of thin films. In this work, our goal is to study the behavior of such systems in thin films, in order to consider the effect of confinement (limited amount of matter, interaction with surface ...) on the process of self-assembly. Thin films are prepared by spin coating and exposed to solvent vapor, providing morphological reorganization. Films are characterized by atomic force microscopy, transmission electron microscopy and grazing-incidence small-angle X-ray scattering. In this presentation, we will describe the conditions to achieve ordered rectangular-shaped cylinders with 4-fold symmetry, oriented perpendicularly to the substrate, providing new appealing type of templates for nanopatterning.
Authors : James Dolan1,2, Karolina Korzeb1, Narjes Abdollahi1, Cédric Kilchoer1, Ulrich Wiesner3, Ullrich Steiner1, Bodo D. Wilts1, and Ilja Gunkel1
Affiliations : 1 Adolphe Merkle Institute, University of Fribourg, 1700 Fribourg, Switzerland; 2 Institute for Molecular Engineering, University of Chicago, Chicago, IL, USA; 3 Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
Resume : Block copolymer (BCP) self-assembly is an effective tool for generating various nanostructured morphologies. Many applications, including nanolithography, photonic structures, and optical metamaterials require precise control of the BCP morphology, i.e. a control of structural order and/or domain orientation. Generating BCP films with long-range order can be realized in an effective manner by controlled solvent vapor annealing. In addition, films of a desired morphology (spheres, cylinders, gyroids, or lamellae) can be produced by annealing films of a single copolymer material in solvent mixtures of tuned selectivity. While this has been investigated in detail for diblock copolymers, the effect of selective solvent annealing has not yet been studied for the more complicated triblock terpolymers. We here present the results of in situ grazing-incidence small-angle x-ray scattering (GISAXS) during solvent annealing of gyroid-forming polyisoprene-b-polystyrene-b-poly(ethylene oxide) triblock terpolymer films. The solvent selectivity was adjusted by using mixed vapor ratios of tetrahydrofuran and methanol. In contrast to diblock copolymers, we found the gyroid morphology forms robustly irrespective of the solvent vapor ratios used for annealing of the terpolymer film. Furthermore, we show that the robust nature of the gyroid morphology allows for generating films with long-range order that are useful, for example, as templates for the fabrication of optical metamaterials.
Authors : Holger Frey, Axel H. E. Müller, Eduard Grune, Marvin Steube, Tobias Johann
Affiliations : Institut für Organische Chemie, Johannes-Gutenberg Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
Resume : Multiblock polymers are abundant in Nature and play a key role for biopolymers with unusual mechanical properties, such as silk fibroin and spider silk, with a linear multiblock structure combining multiple crystalline (i.e., rigid) segments with flexible block. Enormous synthetic efforts is required to prepare multiblock copolymers via established carbanionic polymerization strategie. On the other hand, recent approaches based on living radical techniques afforded multiblock structures with up to 20 blocks, albeit extremely short segments. We capitalize on a one-pot strategy for living AB tapered diblock copolymers. The approach relies on the in-situ monitoring of the simultaneous carbanionic copolymerization for direct observation of the monomer consumption. This method is useful for anionic copoly-merizations carried out in apolar solvents, such as cyclohexane or toluene due to the rather slow reaction kinetics. From the decrease of the monomer concentrations the incorporation probability for each monomer at every position of the polymer chain can be determined with unprecedented precision. In-situ kinetic studies of a variety of carbanionic copolymerizations have been carried out in our group[. Copolymerization of isoprene and p-methyl styrene (I/p-MS) in cyclohexane leads to a strong gradient, since isoprene reacts considerably faster than p-methyl styrene. The in-situ NMR technique enables precise assessment of the comonomer gradient, resulting in extremely divergent reactivity ratios (i.e., r1=33.9 for I and r2=0.026 for p-MS), enabling a one-step synthesis of gradient structures with narrow gradient between both blocks. Repeated addition of isoprene/p-MS mixtures (see arrows in Fig. 1 below) leads to multi-gradient copolymers with up to 14 blocks and elevated molecular weights of up to 520,000 g/mol in 4-5 addition steps (Mw/Mn = 1,05-1,08, 1.36 for 14 blocks). The multi-tapered block copolymers can be prepared on a scale of 100 grams. The materials form ordered phase-segregated nanostructures with high bridging fraction and therefore exhibit high modulus and excellent toughness.
Block-Copolymer Applications - I : Guillaume Fleury
Authors : Igor I. Potemkin, Andrey A. Rudov, Rustam A. Gumerov
Affiliations : Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation DWI − Leibniz Institute for Interactive Materials, Aachen 52056, Germany
Resume : It is well known that stability of solid colloidal particles towards aggregation can be achieved by adsorption of amphiphilic copolymers on the surface of the particles. In many applications diblock copolymers are used: the solvophobic blocks are adsorbed on the surface of the particles and solvophilic blocks protect aggregation (steric stabilization). However, when the colloidal particles are mixed with the diblock copolymers, a competing process of micelle formation reduces efficiency of the diblock copolymers as stabilizers. In the present paper, we propose a model of specially designed amphiphilic AB copolymers which possess low tendency towards intermolecular aggregation and high adsorption ability. The primary structure of the copolymer has elements of a linear triblock copolymer. It contains solvophobic (A) and solvophilic (B) end-blocks and regularly alternating AB multiblock copolymer as a middle block which is surface-active. This block is localized at the core-corona interface of the micelle reducing the aggregation number. We have shown that the aggregation number of the micelles formed by the designed copolymer can be ten times lower than that of the diblock copolymer. Kinetics of adsorption of the designed copolymer on solvophobic surface is compared with that of equivalent diblock copolymer. It is shown that even strong attraction of the molecules to the surface cannot destroy diblock copolymer micelles (at least during simulation time), whereas designed macromolecules form dense planar brush on the surface for a short enough time. We also demonstrated that gradient copolymers have a similar ability as the triblock copolymers. Suppression of the aggregation ability can be also achieved via proper design of architecture of the macromolecules. We have demonstrated that arborescent amphiphilic copolymers practically do not aggregate in selective solvents and reveal fast adsorption on liquid-liquid interfaces efficiently stabilizing emulsions. Also we have demonstrated that polymer microgels possess unique properties for controlled stabilization of the emulsions endowing them by certain functions.
Authors : Yutian Zhu
Affiliations : State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022
Resume : Block copolymer is a type of polymer constituted by different polymer segments covalently linked together. It has been reported that the block copolymer can spontaneously self-assemble into various well-defined nanostructures under certain conditions. When the self-assembly of block copolymer occurs within the emulsion droplet, the confinement effect can effectively break the symmetry of a structure, resulting in the formation of some unique nanostructures which cannot be obtained in bulk state. In the current study, we combine Monte Carlo simulation and experiment to investigate the confined self-assembly of AB diblock copolymer in the emulsion droplet. It is found that the self-assemble nanostructures depend on the confinement size, block copolymer properties, and oil/water interfacial properties. Moreover, we also introduce inorganic nanoparticles into the emulsion droplet to co-assemble with block copolymer. It is found that block copolymer can form some well-defined polymeric scaffolds, which can well direct the distribution and alignment of inorganic nanoparticles in the hybrid particles.
Authors : Stefania Zappia (1), Silvia Destri (1) , Guido Scavia (1), William Porzio (1), Umberto Giovanella (1), Anna Maria Ferretti (2), Varun Vohra (3), Janardan Dagar (4), Thomas M. Brown (4)
Affiliations : (1) Istituto per lo Studio delle Macromolecole (ISMAC), CNR, via A. Corti 12, 20133 Milano, Italy; (2) Istituto di Scienze e Tecnologie Molecolari (ISTM), CNR, Lab. Nanotecnologie, via G. Fantoli 16/15, 20138 Milano, Italy; (3) University of Electro-Communications (UEC), 1-5-1 Chofugaoka, Chofu, Tokyo 182-858, Japan; (4) Università degli Studi di Roma Tor Vergata, Department of Electronics Engineering, Roma, Italy;
Resume : Water-processable organic nanoparticles (NPs) of semiconducting polymers received wide attention for optoelectronic applications due to their simple fabrication and tunable properties. The NP-based approach is appealing to control the morphology of the active layer in optoelectronic devices, such as organic photovoltaics (OPVs), organic light-emitting diodes, and organic field-effect transistors. The miniemulsion method ensures the stability of the water-suspended NPs using insulating surfactants, lowering the chlorinated solvent use for the active layer fabrication. To gain good performances, the surfactant excess has to be removed at the end of the process. [Mater Today 2016, 19, 533] Here we will present a series of amphiphilic low band gap rod-coil block copolymers (BCPs), constituted by a low band-gap polymer, PCPDTBT as electron donor material, and different poly-4-vinylpyridine (P4VP)-based flexible blocks. We studied the capability of these BCPs, neat or in blend with electron acceptor materials, to assembly NP dispersions in aqueous medium through miniemulsion without surfactants, exploiting the hydrophilic coil behavior and avoiding costly purification steps. The coil block features address the assembly in the obtained NPs, neat and blended with fullerene derivatives, leading to the nano-aggregation in the active layers. The relationship between the nano-aggregation of the NPs and the device performances will be discussed. [Adv Sustain Sys DOI:10.1002/adsu.201700155]
Authors : Hyoungwon Park, Tobias Rejek, Marcus Halik
Affiliations : Organic Materials & Devices (OMD), Department of Materials Science, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstraße 7, 91058 Erlangen, Germany
Resume : The block copolymer (BCP) – nanoparticle (NPs) hybrid materials may combine the unique features of nanoparticles with the flexibility, solubility, and processability of polymeric materials. The chemical and physical properties of these nanostructured materials can be tuned by the distribution of particles, which depend on the concentrations, the functionalities, and the size of particles. By matching the surface functionalities of NPs to the polymer subunits in BCP, well-ordered hybrid nanomaterials can be achieved while NPs are selectively enriched in one of the BCP phases . In our experiments, amphiphilic diblock copolymers, consisting of a hydrophobic polystyrene block (PS) and a hydrophilic poly(ethylene oxide) block (PEO), were used as organic matrix. In order to adapt the surface of NPs to the BCP, various metal oxide NPs (TiO2, Al2O3, Fe3O4) were functionalized with self-assembled monolayer (SAM) molecules to endorse the NPs to match the affinities of BCP phases . By changing the functionalities of the SAM molecules, we were able to tune the selective enrichment of the NPs in the specific BCP phases. We investigate the film morphology of thin films created from this material and their respective electrical characteristics in capacitor stacks and organic thin film transistor setups.  H. Zhang, Y. Liu, D. Yao, B. Yang, Chem. Soc. Rev. 2012, 41, 6066.  L. Portilla, M. Halik, ACS Appl. Mater. Interfaces 2014, 6, 5977.
Authors : Hiroshi Yabu
Affiliations : WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, Japan
Resume : Block copolymer phase separation has been employed to form templates for the fabrication of nanoscale pat- terns of metals due to their characteristic size scales that range from several nanometers to tens of nanom- eters; this is still a challenging technique for state-of- art top-down fabrication technologies. To realize well-aligned metallic nanostructures, new materials are required, whose phase-separated structures can be easily aligned and metallized. A catechol group, which is one of the adhesive groups found in the byssus of mussels, has both adhesive and reductive properties due to its two phenolic hydroxyl groups. Poly(3,4-dihydroxystyrene), also known as poly(vinyl catechol) (PVCa), is one of the simplest models of catechol polymers. To avoid unexpected termination and chain transferring due to phenolic hydroxyl groups, protected monomers including dimethoxy styrene (DMSt) have been employed. Based on this background, we have synthesized block copolymers containing catechol moieties, poly(vinyl catechol-block-styrene) (PVCa-b-PSt) and poly(methyl methacrylate-block-vinyl catechol-block-styrene) (PMMA-b-PVCa-b-PSt) by the RAFT polymerization of dimethoxy styrene and styrene followed by deprotection of the methoxy groups. By using adhesion and reductive properties of catechol moieties, metal and inorganic nanoparticle arrays formed inside of block copolymer thin films.
Block-Copolymer Applications - II : Igor Potemkin
Authors : Soonmin Yim, Yeon Sik jung
Affiliations : KAIST
Resume : Despite the outstanding physical and chemical properties of two-dimensional (2D) materials, due to their extremely thin nature, eliminating detrimental substrate effects such as serious degradation of charge-carrier mobility or light-emission yield remains a major challenge. This talk introduces a new strategy based on the insertion of high-density block copolymer (BCP) nanopatterns as an air-gap-containing supporter between 2D materials and substrate to minimize their contact and to block the substrate-induced undesirable effects. We show that well-controlled high-frequency SiOx nanopillar structures derived from the self-assembly of Si-containing block copolymer securely prevents the collapse or deformation of transferred MoS2 and guarantee excellent mechanical stability. The air-gap supporters formed below monolayer MoS2 leads to dramatic enhancement of the photoluminescence emission intensity (8.7-fold), field-effect mobility (2.0-fold, with a maximum of 4.3 fold), and photoresponsivity (12.1-fold) compared to the sample on flat SiO2. Similar favorable effects observed for graphene strongly suggest that this simple but powerful air-gap-supporting method can be extensively applicable to a variety of low-dimensional materials and contribute to improved device performance.
Authors : Paul Nealey
Affiliations : Institute for Molecular Engineering University of Chicago and Argonne National Laboratory
Resume : Directed self-assembly (DSA) is a promising strategy for high-volume cost-effective manufacturing at the nanoscale. Materials that self-assemble form nanostructures with precise, predictable and reproducible dimensions at length scales at the molecular and atomic scale. Unfortunately, the micrometer areas or volumes over which the materials self-assemble with adequate perfection in structure is often incommensurate with the macroscopic dimensions of devices and systems of devices of industrial relevance. Directed self-assembly (DSA) refers to the integration of self-assembling materials with templates to impact structural precision and therefore functionality to self-assembling materials over macroscopic dimensions. Here I will discuss the use of lithographically-defined chemically patterned surfaces to direct the assembly of block copolymers and liquid crystal systems in two and three dimensions for applications in semiconductor manufacturing, ion-conducting membranes, and optoelectronics. In addition, I will highlight the fundamental understanding gained by comparing and contrasting the two materials systems, and how progress in DSA has been enabled and accelerated by a combined experimental and theoretical approach.
Authors : R. I. Rodríguez-Beltrán (1,5), E. Gutiérrez (2), A. Linares (2), A. Nogales (2), S. Paszkiewicz (3), A. Szymczyk (4), Z. Roszaniec (3), T.A. Ezquerra (2), P. Moreno (1), E. Rebollar (5)
Affiliations : (1) Grupo de Aplicaciones del Láser y Fotónica (ALF-USAL), Universidad de Salamanca, Pl. de la Merced s/n, 37008 Salamanca, Spain; (2) Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain; (3) Institute of Material Science and Engineering and (4) Institute of Physics, West Pomeranian University of Technology, PL-70310 Szczecin, Poland; (5) Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain
Resume : Poly(ether-ester) thermoplastic elastomers are segmented block copolymers consisting of alternating sequences of flexile polyether and rigid polyester segments. These block copolymers typically exhibit a phase separation of the softer polyether fraction from the harder polyester one. The late possesses a semicrystalline nature and appears randomly distributed in the soft polyether phase acting as physical cross-links. In comparison with standard di-block copolymers the morphological control of the phase separated copolymers is more complex and requires further understanding. Nanostructuring by laser is an attractive approach to provide laser induced periodic surface structures (LIPSS) on supported amorphous polymer films. However, the preparation of LIPSS either on semicrystalline polymer materials or in free standing polymer films is still challenging. Here, we will present results about nanostructuring by LIPSS on films of poly(trimethylene-terephthalate)-block-poly(tetramethylene-oxide) copolymers. Structural characterization by Atomic Force Microscopy (AFM) and by Grazing Incidence X-ray Scattering at Small angles (GISAXS) reveals that the nanostructuring process proceeds by melting and recrystallization of the semicrystalline domain. The implication of these features on the potential application of this type of block copolymers for templating will be discussed.  Rebollar, E.; Castillejo, M.; Ezquerra, T. A. European Polymer Journal 2015, 73, 162.
Authors : MIchael A Morris
Affiliations : AMBER Trinity College Dublin
Resume : Block copolymers (BCPs) as a patterning technique have developed rapidly over the last 20 years. This has been mainly driven by needs in the semiconductor manufacturing industry since they can provide a low-cost alternative to UV lithography to creating sub 20 nm features at silicon substrates. These features can be used to create transistors or provide interconnects and vias. However, with the disbandment of the ITRS, the future of BCP lithography at device level may be limited and, indeed, the continued scaling that has driven the industry is likely to be of limited value. One possible way forward is vertical integration of devices where memory, sensing and computation is included at back-end-of-line (BEOL). However, developing devices at BEOL is challenging. Such devices are limited by the thermal budget that is allowed and the device materials that can be used. Techniques such as implantation can not be used suggesting silicon is unlikely to be used and more exotic materials need to be considered. However, materials such as 2D and III-Vs are difficult to pattern with sensitivity to etch etc. Block copolymers can be used to create active nanopatterns by selective infiltration and various techniques such as ALD and solvent mediated forms can be used. However, making patterned semiconductor materials have yet to be shown to any great extent. Here we outline the challenges that have to be met and outline how these can be created using insertion of precursors and nanomaterials. Both hexagonal nanodot structures and parallel nanowires of various semiconductors will be shown. Electrical characterisation of these indicate the possibility of the future development and use of these methods.
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Block-Copolymer Applications - III : Michael Morris
Authors : Valerie D. Mitchell, David J. Jones
Affiliations : Department of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Parkville, Melbourne, Victoria, Australia, 3010
Resume : Controlled phase separation between n- and p-type organic semiconductors lies at the core of high performance organic solar cells. Current methods kinetically trap partially phase separated structures, however these often are thermally unstable during operation. We have been examining fully conjugated block copolymers to control morphology development. In this work we report the synthesis, purification, morphological and photovoltaic evaluation of a novel fully-conjugated donor/acceptor block copolymer system based on the P3HT-b-PFTBT scaffold. The incorporation of hydrophilic tetraethylene glycol side-chains into the PFTBT acceptor block generates an amphiphilic species whose properties provide demonstrable benefits over traditional systems. This design strategy facilitates isolation of the block copolymer from homopolymer impurities present in the reaction mixture, and we show that this purification leads to better-defined morphologies. The chemical disparity introduced between donor and acceptor blocks causes spontaneous microphase separation into well-defined domains, which we demonstrate with a combination of spectroscopy, microscopy, and X-ray scattering. The morphological advantages of this system are significant.  Mitchell, V. D., Wong, W. W. H., Thelakkat, M., and Jones, D. J., "The synthesis and purification of amphiphilic conjugated donor–acceptor block copolymers," Polymer Journal, Vol. 49(1), 155-161 (2016). DOI: 10.1038/pj.2016.97  Mitchell, V. D.; Gann, E.; Huettner, S.; Singh, C. R.; Subbiah, J.; Thomsen, L.; McNeill, C. R.; Thelakkat, M.; Jones, D. J., "Morphological and Device Evaluation of an Amphiphilic Block Copolymer for Organic Photovoltaic Applications" Macromolecules 2017, 50 (13), 4942-4951. DOI: 10.1021/acs.macromol.7b00377  Mitchell, V. D., and Jones, D. J., "Advances Towards the Effective Use of Block Copolymers as Organic Photovoltaic Active Layers" Polymer Chem. 2018 (review accepted).
Authors : Alberto Alvarez-Fernandez (1,2), George Hadziioannou (2), Guillaume Fleury (2), Virginie Ponsinet (1)
Affiliations : (1) Centre de Recherche Paul Pascal, Univ. Bordeaux, CNRS UPR 8641, Pessac, France; (2) Laboratoire de Chimie des Polymères Organiques, Univ. Bordeaux, CNRS UMR 5629/ENSCBP, Pessac, France
Resume : Metasurfaces have been gaining increasing attention as they possess demonstrate exceptional abilities for propagation of light, giving rise to properties which are not available by conventional planar and thin interfaces. They usually consist of flat arrays of optical resonators with spatially varying geometric parameters and subwavelength separation, classically fabricated by lithography techniques such as photolithography or electron-beam lithography. We show in this presentation that block copolymer self-assembly give access to a straightforward and versatile nanofabrication method for this type of structures. We present a great variety of metasurfaces, from simple metallic hexagonal dots or continuous metallic lines to more complex structures such us raspberry-like bimetallic nanoclusters, all produced using self-assembled thin films of different molecular weight poly(styrene)-b-poly(2-vinyl pyridine) (PS-b-P2VP) copolymers, synthetized by living anionic polymerization. Grazing-Incidence Small Angle X-ray Scattering, Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Photoelectron Spectrometry, and Kelvin Probe Force Microscopy have been used to follow each step of the fabrication process. Besides, the optical properties of the nanostructured films, strongly affected by their plasmon resonances, are studied by variable-angle spectroscopic ellipsometry.
Authors : Hanna Hulkkonen, Turkka Salminen, Tapio Niemi
Affiliations : Tampere University of Technology, Laboratory of Photonics
Resume : Optical properties of metals are often characterized by high reflectance and losses. Recently, "total" optical absorption in metal films has been of interest in applications such as biosensing, nonlinear optics and solar energy harvesting. Attempts to enhance the absorption have been made by depositing lossy dielectric or semiconductor thin films on metals or by nanostructuring the surface . Here we have combined block copolymer lithography (BCP) with a template stripping process to create metasurfaces that exhibit strong light absorption in the visible range. An inverse pattern was etched onto a Si wafer using a mask made from poly(styrene-vinylpyridine) as described previously . A thin layer of Au was deposited on the patterns and a support was attached on top using UV-curable epoxy. Due to the poor adhesion of Au on Si, the top layers could be cleanly separated from the Si mold revealing a high-quality nanostructured Au film. BCP lithography can produce sub-wavelength structures over large areas with ease and template stripping enables the transfer of patterns onto a variety of rigid, flexible and curved substrates. The Au films could absorb > 95% of light up to 550 nm, which could also be seen as altered coloring. We expect to incorporate the material into sensor surfaces and plasmonic devices that generate energetic (hot) electrons.  Kats M, Capasso F, Las. Photon. Rev. 2016;5(735)  Hulkkonen H, Salminen T, Niemi T, ACS Appl. Mater. Interfaces. 2017;9(37)
Block-Copolymer Applications IV : David Jones
Authors : Marleen Kamperman
Affiliations : Wageningen University & Research Physical Chemistry and Soft Matter Stippeneng 4 6708 WE Wageningen the Netherlands
Resume : The adhesive secretions of marine animals such as P. californica and M. edulis combine covalent and non-covalent interactions to afford strong underwater adhesion. Characteristic of the proteins found in the adhesive plaque of mussels and sandcastle worms is a high proportion of cationic, anionic and catecholic residues (hydroxylated tyrosine, DOPA). DOPA is involved in a versatile combination of functions: covalent crosslinking, complexation to mineral substrates, and bonding to hydrophobic (fouled) surfaces. The anionic and cationic residues are often said to be involved in a secondary interaction that aids cohesion, namely complex coacervation. This is an attractive phase separation of mixtures of polyanions and polycation that results in a highly polyelectrolyte-rich phase in equilibrium with almost pure solvent. Complex coacervates have very low surface tensions, which makes them highly desirable as non-water soluble adhesive agents. Additionally, they are mechanically very well-suited to adhesion due to their high storage and loss moduli that provide, respectively, bonding strength and dissipation of strain. In this study, we aim at reproducing the working mechanism of mussels and sandcastle worms by developing a new class of underwater block copolymer adhesives based on complex coacervates reinforced with physical interactions.
Authors : K. Brassat, A. Brüngeler, W. Bremser, O. I. Strube, J. K. N. Lindner
Affiliations : Nanostructuring, Nanoanalysis and Photonic Materials group, Dept. of Physics, Paderborn University, Germany; Center for Optoelectronics and Photonics Paderborn CeOPP, Paderborn, Germany; Biobased and bioinspired materials group, Dept. of Chemistry, Paderborn University, Germany
Resume : Block copolymer (BCP) lithography allows for the large-area structuring of surfaces with self-assembled nanopatterns. In particular, nanopores with diameters in the sub-20 nm regime can be easily created on different material surfaces. Nanopores in this size regime are of great interest in bionanotechnology and biomedicine, because proteins and cells interact with surfaces at exactly this length scale. In this contribution, we give an example of how the controlled nanopatterning of TiO2 surfaces by BCP nanopores allows for experiments which give insight into the interactions between biological units and the nanopatterns. We create arrays of proteins on surfaces by combining block copolymer lithography as surface prepatterning technique and enzyme mediated autodeposition. A material contrast between the free substrate areas inside the BCP nanopores and the BCP thin film allows for the site-selective assembly of proteins. In particluar, melanin proto-particles are formed by a surface-near L-DOPA polymerization, which takes place site-selectively inside the nanopores the bottom of which is functionalized with covalently bonded tyrosinase. The biomolecule arrays are investigated by AFM, SEM and XPS. Such arrays allow for their use as biocompatible surfaces for cell investigations, which are subject of ongoing studies.
Authors : Anna Malafronte, Claudio De Rosa, Finizia Auriemma
Affiliations : Dipartimento di Scienze Chimiche Università di Napoli Federico II
Resume : Immobilization of enzymes using nanoporous supports is a growing area of research, since the large surface area of nanoporous materials and their opened porous structure can afford the stabilization of biomolecules, improve enzyme loading and increase enzyme activity. We have set up a versatile and easy procedure for fabrication of supports with tailored nanoporosity for immobilization of enzymes, by using self-assembly of block copolymers (BCPs) and the concept of sacrificial blocks. Nanostructured thin films with well-defined architecture containing pores of tailorable size delimited by walls with tailorable degree of hydrophilicity have been obtained. A mixture of polystyrene-block-poly(L-lactide) (PS-PLLA) and polystyrene-block-poly(ethylene oxide) (PS-PEO) BCPs has been employed to generate thin films with a lamellar morphology consisting of PS lamellar domains alternating with mixed PEO/PLLA blocks lamellar domains. Selective basic hydrolysis of the PLLA blocks generates thin films, patterned with nanometric channels containing hydrophilic PEO chains pending from PS walls. It is demonstrated that the designed support is suitable for adsorption and nanoconfinement of specific biomolecules, such as the enzyme peroxidase from horseradish (HRP). The immobilized HRP shows improved catalytic performance, no mass-transfer limitations, and long-term stability, compared with that of enzyme immobilized onto flat supports.
Authors : Christine Schulte-Osseili, Sophia Böcker, Alexander Böker, Ruben R. Rosencrantz
Affiliations : Fraunhofer Institute for Applied Polymer Research IAP, Chair of Polymer Materials and Polymer Technologies, University Potsdam, Geiselbergstraße 69, 14476 Potsdam, Germany
Resume : Glycan-driven interactions play a key role in molecular recognition processes in nature. Various pathogens with clinical relevance like Helicobacter pylori, Pseudomonas aeruginosa, Clostridium difficile or uropathogenic E. coli express glycan-binding lectins so called adhesins on their cell-surface or as domain of their toxins, which are used to attach and invade the host-cells. This can be used to target pathogens by designing structures equipped with suitable glycan-ligands. We first introduce a novel double-hydrophilic hydroxyethylmethacrylate (HEMA) based diblock glycopolymer which self-assembles into homogeneous spherical micellar structures in water. The micellar structure renders surface-oriented N-acetylglucocosamine (GlcNAc) sugar moieties for strong multivalent glycan-mediated lectin binding. Structural analysis and lectin binding is performed by microscopy methods, dynamic light scattering (DLS) and two-focus fluorescence correlation spectroscopy (2fFCS), revealing a novel micellar type of multivalent sugar binding scaffold. The next step is the synthesis of more stable block copolymers containing a PMMA and a mannose glycopolymer block. Mannose is known to be a ligand for the virulence factor FimH, which is expressed by uropathogenic E. coli. The copolymers form micelles in aqueous solution which can be loaded with hydrophobic dyes. Biofunctionality of the polymers could be shown by the interaction with mannose-binding lectin ConA analyzed by isothermal titration calorimetry. The fluorescence spectroscopy measurements using two different model E. coli strains revealed strong glycan dependent interactions and depicted the influence of the polymer structure on the binding efficiency. Interestingly, we found size- and glycopolymer block length dependent binding of the micelles by E. coli. It is possible to tune the polymer structure to receive strain-specific binding by still addressing the same kind of glycan-driven biomolecular interactions. Applications of the micelles range from diagnostic functions like specific labeling of pathogenic microorganisms to encapsulation and specific transport of hydrophobic drugs or antibiotics for therapy.
Authors : Barry Reid (1), Alaric Taylor (1), Yinong Chen (1), Benjamin Schmidt-Hansberg (2) and Stefan Guldin (1)*
Affiliations : (1) Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K. (2) Chemical & Process Engineering, Coating & Film Processing, BASF SE, Carl-Bosch-Strasse 38, Ludwigshafen am Rhein 67056, Germany.
Resume : Generating mesoporous films with adequate film thickness and refractive index is a common method to achieve amplitude and phase matching in low-cost interference-based antireflective coatings (ARCs). For high surface energy materials, mesopores are subject to capillary condensation by surrounding atmospheric water molecules, reducing their functionality. In this work, we examine the effect of relative humidity on mesoporous ARCs and present a simple method for the preparation of ARCs with robust operation under variable conditions. The materials route is based on the generation of well-defined porous aluminosilicate networks by block copolymer co-assembly with poly(isobutylene)-block-poly(ethylene oxide) and post-synthesis grafting of hydrophobic molecules to the pore walls. In-situ ellipsometric porosimetry and light transmittance measurements enables the comprehensive characterisation of the ARC properties under variable humidity. Our functionalized films exhibit a maximum transmittance value of 99.8% with an average transmittance of 99.1% in the visible wavelength range from 400 nm to 700 nm. Crucially, the AR performance is maintained at high humidity values with an average transmittance decrease of only 0.2% and maximum values maintained at 99.7%. The ARCs are able to withstand repeated humidity cycles, indicating long-term stability against fluctuating environmental conditions.
Block-Copolymer Applications - V : Marleen Kamperman
Authors : Thomas H. Epps, III, Melody A. Morris, Wei-Fan Kuan, Thomas E. Gartner, III
Affiliations : Dept. of Chemical and Biomolecular Engineering, Dept. of Materials Science and Engineering
Resume : Block copolymers (BCPs) are an exciting class of soft materials that enable controlled phase separation and nanoscale self-assembly of designer macromolecules for applications ranging from thermoplastic elastomers and membranes to nanocapsules for drug delivery. One subclass of block copolymers, tapered block copolymers (TBCs), offers a unique opportunity for optimizing thermal, mechanical, and transport properties in BCPs through control of the monomer distribution near the junction between the copolymer blocks. We have synthesized various TBCs containing normal and inverse tapers, of various lengths and compositions, by using semi-batch feeds in combination with ‘living’ anionic and/or controlled radical polymerizations. Through this approach, we are able to generate a diverse array of well-organized and self-assembled nanostructures, while improving mechanical properties or reducing processing temperatures relative to traditional BCPs. Additionally, we recently have reported ion-conducting copolymer systems in which judicious choice of taper geometry led to reductions in block glass transition temperatures, which ultimately reduced barriers to ion-transport and enhanced conductivity.
Authors : Preston Sutton, Ulli Steiner, Ilja Gunkel
Affiliations : Adolphe Merkle Institute University of Fribourg Chemin des Verdiers 4 CH-1700 Fribourg Switzerland
Resume : Polyethylene oxide (PEO) containing block copolymers (BCPs) have become popular systems to explore the fundamentals of lithium ion transport in solid polymer electrolytes. They allow unique morphological network structures and each block can be selected for a specific characteristic or role. This one-function-per-block tailoring can enhance the entire system by decoupling normally linked properties. For example, mechanical strength can be decoupled from conductivity, eliminating their antagonistic dependence on viscosity found in the PEO homopolymer. ISO triblock terpolymers (polyisoprene-b-polystyrene-b-polyethylene oxide), relative to diblocks, also give more reliable access to the continuous 3D structure required for maximum conductivity. In ISO, a non-conducting PS block maintains mechanical stability independently of the conducting PEO phase, while the rubbery PI block, results in a system that preferentially self-assembles into a robust 3D gyroid network. While this strategy overcomes the mechanical problems of PEO homopolymer at different temperatures, the properties of block-confined PEO, including conductivity, crystallinity, and structure are distinct from the homopolymer and must be characterized for individual electrolyte systems. Here, ISO of various molecular weights (Mn) plus LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) demonstrate the effects of glass transition (Tg), Mn, and grain size, on the ionic conductivity of a potential BCP battery electrolyte. Our DSC and EIS results suggest that the Tg of PS, which is a function of Mn, needs to be minimized to prevent the glassy block from impeding PEO chain motion essential to ionic transport1. This result shows that the Tg of a non-conducting block must also be considered during BCP electrolyte design. Another finding draws a distinction between the previously reported tendency for a lithium perchlorate doped ISO system to form a 2D cylindrical morphology2. The substitution of LiTFSI maintains the continuous 3D network important for maximum conductivity. We additionally show that the as-cast continuous network system is disorganized compared to the long-range gyroid, but nevertheless effective, precluding the need for annealing.
Authors : Michael Handl; Tobias Morawietz; K. Andreas Friedrich; Renate Hiesgen
Affiliations : University of Applied Sciences Esslingen, 73728 Esslingen, Germany; University of Applied Sciences Esslingen, 73728 Esslingen, Germany; German Aerospace Center, Institute of Engineering Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany; University of Applied Sciences Esslingen, 73728 Esslingen, Germany
Resume : Today?s most common membranes for proton exchange membrane fuel cells ? perfluorosulfonic acid (PFSA) membranes like Nafion or Aquivion ? still suffer from severe drawbacks such as poor mechanical stability at high temperatures, low ionic conductivity at low humidification, high gas crossover and high costs. To overcome these drawbacks new, alternative materials, in particular sulfonated random and multiblock-copolymers, are in the focus of research. Even if they show comparable and even superior properties as membrane, their performance can often not compete with PFSA ionomers when incorporated into fuel cells. Reasons for that are low oxygen diffusion in electrodes and delamination of electrodes, for example. For better understanding of the inferior performance in fuel cells, morphology and ion conductive structure were investigated at nanometer scale by a material sensitive, conductive AFM. Cross-sections and surfaces of sulfonated poly(phenylene sulfone) multiblock-copolymers were examined as recast membranes at different humidification levels. Furthermore, ultra-thin, self-assembled layers on substrates of different surface energies were investigated on their morphology and ion conductive structure for modeling polymer structure in fuel cell electrodes. Analysis of the ionic conductive structure dependent on the layer thickness of the ultra-thin layers, gave additional valuable information about the polymers behavior in fuel cell electrodes.
Authors : Dinglei Zhong, Zhaogen Wang, Yong Wang*
Affiliations : Membrane Science & Technology Research Center; State Key Laboratory of Materials-Oriented Chemical Engineering; Nanjing Tech University
Resume : High permeability is one of the most important pursuits of membrane-based water treatment. In our work, asymmetric membranes with a thin skin layer and a fingerlike matrix are firstly prepared by nonsolvent-induced phase separation (NIPS) of an amphiphilic block copolymer, polysulfone-block-poly (ethyleneglycol) (PSF-b-PEG). After subsequent selective swelling of the membranes, mesopores are generated in the skin layer and the PEG blocks are selectively enriched on the membrane surface. The produced membranes exhibit simultaneously upgraded hydrophilicity, permeability, and fouling resistance. For instance, one membrane possessing 75% rejection to BSA can give a water permeability as high as 750 L·m-2·h-1·bar-1. Interestingly, by tailoring the swelling conditions, such as swelling reagents, durations and temperatures, the performances of the membranes can be tuned in a relatively wide range. Fouling resistance of the PSF-b-PEG membranes is also enhanced, which is ascribed to the enrichment of PEG on the surface. Besides, due to the nondestructive nature of the selective swelling process, the mechanical properties of the membranes are maintained. This two-step strategy is expected to be applied to fabricate other block copolymer membranes with tuned structures and improved performances.
Authors : Michele Perego (1), Morgan Stefik (2), Guillaume Fleury (3), Francesc Perez-Murano (4)
Affiliations : (1) Laboratorio MDM, IMM-CNR, Via Olivetti 2 Agrate Brianza Italy (2) University of South Carolina Department of Chemistry and Biochemistry - 541 Main st, Columbia, SC 29208, USA (3) University of Bordeaux, LCPO 16 avenue Pey Berland, 33607 Pessac Cedex, France (4) Institute of Microelectronics of Barcelona (IMB-CNM, CSIC) Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
Resume : Final considerations
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