Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session V52: Block Copolymer Thin Films II: Experiment and ApplicationFocus
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Sponsoring Units: DPOLY Chair: Julie Albert, Tulane University Room: BCEC 253B |
Thursday, March 7, 2019 2:30PM - 3:06PM |
V52.00001: Sequential Infiltration Synthesis – Mechanism and Applications of Metal Oxide Growth within Block Copolymers Invited Speaker: Tamar Segal-Peretz Sequential infiltration synthesis (SIS) is an emerging technique which harnesses atomic layer deposition (ALD) chemistry for growth of inorganic materials within polymers. The highly selective growth within the polar domains of block copolymers (BCP) makes it attractive method for fabricating hybrid BCP-metal oxide composite with synergic properties as well as for BCP-templated inorganic nanostructure fabrication. However, complete understanding of SIS mechanism is still missing and exploring its application space has only just began. |
Thursday, March 7, 2019 3:06PM - 3:18PM |
V52.00002: Self-Assembly Kinetics Enhancement in Ternary “Wet Brush” Block Copolymer/Homopolymer Blend Thin Films Gregory Doerk, Ruipeng Li, Masafumi Fukuto, Alfredo Rodriguez, Kevin G. Yager In this talk we discuss our recent work investigating the enhanced ordering kinetics in thin film ternary blends of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymers with low molecular weight “wet brush” PS and PMMA homopolymers that distribute more uniformly throughout the domains. In lamellar thin films, blending dramatically increases the power law exponent governing the development of long-range order during thermal annealing. For cylinders the impact of blending is more dramatic in films thicker than one monolayer due to rapid early stage ordering and faster domain reorientation with respect to the substrate. This blending strategy is also compatible with solvent vapor annealing, where it is applied to promote rapid self-assembly of ultrahigh molecular weight PS-b-PMMA (> 1000 kg/mol). The robust enhancement in ordering kinetics afforded through wet brush homopolymer blending is attributed to changes in the effective segregation strength. |
Thursday, March 7, 2019 3:18PM - 3:30PM |
V52.00003: Block Copolymer Films Showing Dual Patterns Using Topographically-Defined Substrates Elisheva Michman, Marcel Langenberg, Roland Stenger, Marcus Mueller, Roy Shenhar Directed self-assembly of block copolymers facilitates the creation of films with highly oriented domains over large areas. However, further enhancing our control over surface design requires the ability to create regions of a desired pattern which could be arbitrarily spaced. |
Thursday, March 7, 2019 3:30PM - 3:42PM |
V52.00004: Block Copolymer Derived Uniform Mesopores For Supercapacitors Guoliang Liu, Tianyu Liu High mass loading and fast charge transport are two crucial but often mutually exclusive characteristics of pseudocapacitors. On conventional carbon supports, high mass loadings inevitably lead to sluggish electron conduction and ion diffusion due to the thick pseudocapacitive layer and clogged pores. Herein from the macromolecular perspective, we revolutionize the design of carbon supports. Utilizing block copolymers that microphase-separate, we synthesize porous carbon fibers (PCFs) with uniform mesopores, which are partially filled with MnO2. The uniform mesopores and ultrathin MnO2 enable fast electron/ion transport comparable to carbons in electrical double layer capacitors. The gravimetric and areal capacitances of MnO2 reach 1148 F/g and 3141 mF/cm2, respectively. |
Thursday, March 7, 2019 3:42PM - 3:54PM |
V52.00005: Multi-scale Block Copolymer Coating That Induces Hydrophobic Properties on Inorganic Surfaces Li-Chen Cheng, John William Simonaitis, Mukarram Tahir, Karim Gadelrab, Yi Ding, Alfredo Alexander-Katz, Karl K Berggren, Caroline Anne Ross Superhydrophobic surfaces hold promise of a technology with various applications spanning different environments, service conditions and length scales. We demonstrated a cost-effective and robust method for imparting superhydrophobicity to target surfaces through self-assembly of block copolymers (BCPs), while the optical properties of underlying materials are preserved. Our approach involves iterative steps of spin-coating, annealing, and etching of different molecular weight (MW) PS-b-PDMS BCPs into multi-layer hierarchal structure. The resulting periodic pattern introduces necessary nanoscale roughness to trap air and increases hydrophobicity of surfaces, and can be controlled by altering tuning parameters such as MW and composition of BCPs. To understand how superhydrophobicity emerged from multi-layer hierarchal BCP structures, multilayer BCP models were constructed by matching experimental observed dimensions, sweeping through wetting configurations, and calculating externally observed contact angles. The results verified the observed experimental trend, demonstrating superhydrophobicity behavior through modulation of roughness at different layers and formation of air pockets. This technology fulfills a pressing need for superhydrophobicity in optically sensitive settings. |
Thursday, March 7, 2019 3:54PM - 4:06PM |
V52.00006: Generalized method for perpendicular orientation of block copolymer microdomains in thin films with surface crosslinking process Jinwoo Oh, Hyo Seon Suh, Jeong Gon Son Sub-10 nm pattern prepared by directed self-assembly of block copolymer (BCP) thin film can be a breakthrough beyond the resolution limitation of conventional photolithography. In the BCP thin film, the vertical orientation of the nanostructures is essential for pattern transfer and lithographic applications, but the surface and interfacial energies of the two domains of the BCPs are different and generally form parallel orientations. Here, we introduced more generalized method for the BCP films to form the perpendicular orientation by cross-linking process to the surface of the BCP film. By effectively cross-linking the surface of a randomly existing BCPs, the cross-linked BCP layer can be worked as natural-born fraction-tailored neutral brush. The cross-linking method can be directly applied to the poly(styrene-block-methyl methacrylate), poly(styrene-block-dimethylsiloxane) and poly(styrene-block-2-vinylpyrdine) films to realize perpendicular orientation from the top surface after thermal/solvent annealing on pristine Si or pre-patterned substrate for chemo-epitaxy directed self-assembly. Also, perpendicular orientation from the bottom interface can be also realized by introducing the new BCP film onto the cross-linked BCP layer. |
Thursday, March 7, 2019 4:06PM - 4:18PM |
V52.00007: Modification Toward Fluorine-Containing High-χ Block Copolymers and Orientation Control on Thin Films Seongjun Jo, Seungbae Jeon, Taesuk Jun, Du Yeol Ryu To approach miniaturized patterns such as sub-10 nm, block copolymer (BCP) has emerged as an attractive material to overcome the size limit of the conventional lithography, where Flory-Huggins interaction parameter (χ) plays the key role to control the size. In this study, fluorine-containing high-χ BCP is newly designed which was synthesized using transesterification method. High-yield conversion was achieved using a polymeric catalyst, where the polymer dispersity remain unchanged during the transesterification. Evaluated χ was above 0.2 over the entire temperature range which is 8 fold higher than polystyrene-b-poly(methyl methacrylate) and the smallest half-pitch feature size was approximately 5 nm from 6.3 kg/mol BCP. Film experiments were demonstrated on a neutralized homopolymer mat substrate where a sub-10 nm perpendicular lamellar morphology was observed in as spun state. |
Thursday, March 7, 2019 4:18PM - 4:30PM |
V52.00008: Self-organization of Triblock Copolymer Melt Chains Physisorbed on Non-neutral Surfaces Daniel Salatto, Naisheng Jiang, Xiaoyu Di, Chang-Yong Nam, Masafumi Fukuto, Maya Endoh, Tadanori Koga Polymer physisorption is an unavoidable event even when weakly attractive surfaces contact a polymer melt. We report the self-organization process of poly(styrene-b-ethylene/butadiene-b-styrene) (SEBS) triblock copolymer chains physically adsorbed on a non-neutral surface. The results revealed that the SEBS chains form the two different chain structures on the substrate simultaneously: (i) “flattened chains” with an average height of 2.5 nm, but without forming microdomain structures; (ii) “loosely adsorbed chains” with an average height of 11.0 nm forming perpendicular oriented cylindrical microdomains to the substrate surface. In addition, it was found that the lateral microdomain structures were distorted and the characteristic length of the microdomains varied from the bulk after reaching the quasi-equilibrium state. Furthermore, we highlight the role of the adsorbed chains in the self-assembling process of the entire SEBS thin film: A long-range perturbation propagates into the film interior, overwhelming the free surface effect associated with surface segregation of the lower surface tension of polystyrene blocks. |
Thursday, March 7, 2019 4:30PM - 4:42PM |
V52.00009: Fabrication of Dual Nanopatterns at desired area using Block Copolymer Containing Photocleavable Linker Chungryong Choi, Soyeong Park, Yeseong Seo, Jaeyong Lee, Seonghyeon Ahn, Eunseol Kim, Jin Kim Block copolymers (BCPs) with various nanodomains, such as spheres, cylinders, and lamellae, have received attention for their nanolithography application. However, those microdomains are determined by the volume fraction of one block. Meanwhile, nanopatterns with multiple shapes are required for the next-generation nanolithography. Although various methods have been reported to achieve dual nanopatterns, all the methods need sophisticated processes using E-beam. Here, we synthesized two kinds of BCP, linear and miktoarm typed BCP, containing o-nitrobenzyl alcohol(ONB) as photo-cleavable linker. In the case of linear BCP, dual nanopatterns consisting of nano-dots and nano-hole were easily fabricated by changing the wavelength of ultraviolet (UV) light. We also fabricated dual nanopatterns consisting of dots and lines at desired regions on a single substrate using miktoarm typed BCP. |
Thursday, March 7, 2019 4:42PM - 4:54PM |
V52.00010: Development of Shape-Tuned, Monodisperse Block Copolymer Particles through Solvent-Mediated Particle Restructuring Jae Man Shin, Young Jun Lee, Mingoo Kim, Kang Hee Ku, Junhyuk Lee, YongJoo Kim, Hongseok Yun, Bumjoon Kim Controllability of the shape, size, and internal structure of block copolymer (BCP) particles as well as their uniformity is crucial to determine their functionality in the practical applications. Here, we demonstrate the particle restructuring by solvent engineering (PRSE) strategy to produce monodisperse particles using functional BCPs with well-defined structure. Importantly, the advantage of PRSE is the general applicability to various types of functional BCPs including polystyrene-block-poly(1,4-butadiene) (PS-b-PB), polystyrene-block-polydimethylsiloxane (PS-b-PDMS), and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP). PRSE starts with producing monodisperse BCP spheres in a wide range of particle size using membrane emulsification, followed by transformation to shape-anisotropic BCP particles by solvent annealing. Monodispersity of particle size was maintained during the PRSE, and the shape transformations to prolate and oblate ellipsoids were successfully achieved. PRSE was also effective in controlling the aspect ratio (AR) of the particles, which was supported by theoretical calculation for describing the particle elongation. Further investigation on the kinetics during the PRSE revealed that the morphology transformation was driven by reorientation of BCP domains. |
Thursday, March 7, 2019 4:54PM - 5:06PM |
V52.00011: Order-to-disorder transition of block copolymer thin films and its dependence on thickness and preferential interaction Jaeup Kim, Daeseong Yong, Yeongsik Kim, Du Yeol Ryu Unlike the phase transitions in the bulk block copolymers (BCPs), the order-to-disorder transition (ODT) in film geometry is influenced by interfacial interactions. An intuitive prediction is that a preferentially selective interaction toward one block promotes microphase separation. Such a prediction is supported by a few theoretical and experimental reports, but a few studies including thermally generated defects or field fluctuation effects suggested an increase in (χN)ODT value with decreasing film thickness. In this study, we focus on the phase transition behavior of cylinder- and lamella-forming block copolymer films subject to an asymmetric wetting condition. Our self-consistent field theory calculation using a discrete bead-spring model with finite-range interactions exhibits a decrease in (χN)ODT with decreasing film thickness for both lamella- and cylinder-forming BCP films. This result is consistent with our expeirments using PS-b-P2VP BCP films with an asymmetric wetting condition that confines the films with selective interactions of the PS/air and P2VP/substrate. For both theory and experiment, the onset of the ODT shift was much thicker for the lamellar case (~20 layers) than for the cylinder case (~10 layers). |
Thursday, March 7, 2019 5:06PM - 5:18PM |
V52.00012: Directional Alignment of Quasi-Single-Crystalline 2D Dot Array in Diblock Copolymer Thin Films via Epitaxial Cylinder-to-Sphere Transition Ye Chan Kim, So Youn Kim Despite the great applicability of block copolymer (BCP) thin films capable of producing dense periodic nanostructures, the difficulty to control the pattern orientation acts as an obstacle to the successful bottom-up lithography of BCPs. The production of guiding pattern on the substrate such as grapho- or chemo- epitaxy has been suggested to create highly ordered nanostructures. However, these methods can be experimentally complicated and expensive, particularly in a large-area. |
Thursday, March 7, 2019 5:18PM - 5:30PM |
V52.00013: Pore Size Control using Cooperative Assembly with Block Copolymers and Low Volatility Solvents Meeta Trivedi, Bryan Vogt Block copolymers (BCPs) provide a facile avenue to the generation of nanoporous materials with well-defined pore geometries. Cooperative assembly of BCPs with functional precursors enables families of materials to be fabricated from a single BCP template. However, the pore size is generally controlled by the BCP, which can be limiting for applications. Here, we demonstrate the ability to effectively tune the pore size (both up and down) through the addition of low volatility solvents during triconstituent co-assembly of carbonizable and silica precursors with a commercial block copolymer (Pluronic F127) that are fabricated by film casting on roll-to-roll equipment. Four different low volatility solvents with varying selectivity were examined. The pore size obtained depends on the hydrophobicity, volatility, and relative amount of solvent added. This enables mesoporous carbon-silica materials with pore sizes ranging from 5 nm to 12.8 nm. The morphology of these materials was elucidated with transmission electron microscopy (TEM) and small angle x-ray scattering (SAXS) to understand how these solvent additives impact the ordered structure. |
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