Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session C9: Symposium Honoring Ed Kramer - Block Copolymers, Nanoparticles, and ConductionFocus
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Sponsoring Units: DPOLY Chair: Rachel Segalman, University of California, Santa Barbara Room: 268 |
Monday, March 13, 2017 2:30PM - 3:06PM |
C9.00001: Orientation and Order in Shear-Aligned Thin Films of Cylinder-Forming Block Copolymers. Invited Speaker: Richard Register The regularity and tunability of the nanoscale structure in block copolymers makes their thin films attractive as nanolithographic templates; however, in the absence of a guiding field, self-assembly produces a polygrain structure with no particular orientation and a high density of defects. As demonstrated in the elegant studies of Ed Kramer and coworkers, graphoepitaxy can provide local control over domain orientation, with a dramatic reduction in defect density. Alternatively, cylindrical microdomains lying in the plane of the film can be aligned over macroscopic areas by applying shear stress at the film surface. In non-sheared films of polystyrene-poly(n-hexylmethacrylate) diblocks, PS-PHMA, the PS cylinder axis orientation relative to the surface switches from parallel to perpendicular as a function of film thickness; this oscillation is damped out as the fraction of the PS block increases, away from the sphere-cylinder phase boundary. In aligned films, thicknesses which possess the highest coverage of parallel cylinders prior to shear show the highest quality of alignment post-shear, as measured by the in-plane orientational order parameter. In well-aligned samples of optimal thickness, the quality of alignment is limited by isolated dislocations, whose density is highest at high PS contents, and by undulations in the cylinders' trajectories, whose impact is most severe at low PS contents; consequently, polymers whose compositions lie in the middle of the cylinder-forming region exhibit the highest quality of alignment. The dynamics of the alignment process are also investigated, and fit to a melting-recrystallization model which allows for the determination of two key alignment parameters: the critical stress needed for alignment, and an orientation rate constant. For films containing a monolayer of cylindrical domains, as PS weight fraction or overall molecular weight increases, the critical stress increases moderately, while the rate of alignment drastically decreases. As the number of layers of cylinders in the film increases, the critical stress decreases modestly, while the rate remains unchanged; substrate wetting condition has no measurable influence on alignment response. [Work of Raleigh Davis, in collaboration with Paul Chaikin.] [Preview Abstract] |
Monday, March 13, 2017 3:06PM - 3:18PM |
C9.00002: Ordering and partitioning in vesicle forming block copolymer thin films Andrew Parnell, Yohei Kamata, Richard Jones Cell biology routinely uses encapsulation processes to package a payload and transport it to a location where the payload can then be used. Synthetic polymer based liposomes (Polymersomes) are one possible way in which we can artificially contain a molecule of interest that is protected from its surrounding environment. Encapsulation technologies at present rely on forming a lipid vesicle and then extruding it in a solution containing the target molecule to be encapsulated. Only a small fraction is encapsulated in this process. This is because of the complex structural formation pathway in going from individual isolated amphiphilic molecules into vesicle aggregates. My talk will discuss strategies to overcome the formation pathways, by forming a block copolymer film with the target molecule and then solvent ordering prior to the formation of vesicles. By studying block copolymer thin films with neutron reflectivity and ellipsometry we are able to observe partitioning and ordering which is essential for high encapsulation efficiencies. [Preview Abstract] |
Monday, March 13, 2017 3:18PM - 3:30PM |
C9.00003: Magnetic field alignment of coil-coil diblock copolymers and blends via intrinsic chain anisotropy Yekaterina Rokhlenko, Pawel Majewski, Steven Larson, Kevin Yager, Padma Gopalan, Apostolos Avgeropoulos, Edwin Chan, Chinedum Osuji Magnetic fields can control alignment of self-assembled soft materials such as block copolymers provided there is a suitably large magnetic susceptibility anisotropy present in the system. Recent results have highlighted the existence of a non-trivial intrinsic anisotropy in coil-coil diblock copolymers, specifically in lamellar-forming PS-b-P4VP, which enables alignment at field strengths of a few tesla in systems lacking mesogenic components. Alignment is predicated on correlation in the orientation of end-end vectors implied by the localization of block junctions at the microdomain interface and is observed on cooling across the order-disorder transition in the presence of the field. For appropriate combinations of field strength and grain size, we can leverage intrinsic chain anisotropy to magnetically direct self-assembly of many non-mesogenic systems, including other coil-coil BCPs like PS-b-PDMS and PS-b-PMMA, blends of BCPs of disparate morphologies and MWs, and blends of BCPs with homopolymers. This is noteworthy as blends of PS-b-P4VP with PEO provide a route to form functional materials such as nanoporous films by dissolution of PEO, or aligned ion conduction materials. We survey these various systems using TEM and in-situ X-ray scattering to study the phase behavior and temperature-, time- and field- dependent dynamics of alignment. [Preview Abstract] |
Monday, March 13, 2017 3:30PM - 3:42PM |
C9.00004: Connecting ion transport in polymer electrolytes across length scales Ksenia Timachova, Lisa Cirrincione, Steven Greenbaum, Nitash Balsara Ion transport in polymers has been extensively studied in an attempt to improve upon the disadvantages of conventional liquid electrolytes. We combine pulsed-field gradient NMR diffusion measurements with electrochemical transport measurements in ethylene oxide based homo and block copolymer electrolytes in order to elucidate some of the connections between macroscopic properties like conductivity and molecular architecture, diffusion, and electrostatic interactions. In homopolymer electrolytes, a single diffusion coefficient governs transport from the micro to the mesoscale. In block copolymers, multiple diffusion regimes are seen at different length scales; diffusion on the microscale is faster than that on the mesoscale. In both materials, the strength of molecular interactions dictates how these molecular diffusion coefficients connect to macroscopic transport. We discuss how molecular interactions and diffusive processes inform bulk ion transport in polymer electrolytes. [Preview Abstract] |
Monday, March 13, 2017 3:42PM - 3:54PM |
C9.00005: Multivalent Ion Transport in Polymers via Metal-Ligand Coordination Gabriel Sanoja, Nicole Schauser, Christopher Evans, Shubhaditya Majumdar, Rachel Segalman Elucidating design rules for multivalent ion conducting polymers is critical for developing novel high-performance materials for electrochemical devices. Herein, we molecularly engineer multivalent ion conducting polymers based on metal-ligand interactions and illustrate that both segmental dynamics and ion coordination kinetics are essential for ion transport through polymers. We present a novel statistical copolymer, poly(ethylene oxide-stat-imidazole glycidyl ether) (i.e., PEO-stat-PIGE), that synergistically combines the structural hierarchy of PEO with the Lewis basicity of tethered imidazole ligands (x$_{\mathrm{IGE}}=$0.17) required to coordinate a series of transition metal salts containing bis(trifluoromethylsulfonyl)imide anions. Complexes of PEO-stat-PIGE with salts exhibit a nanostructure in which ion-enriched regions alternate with ion-deficient regions, and an ionic conductivity above 10$^{\mathrm{-5}}$ S/cm. Novel normalization schemes that account for ion solvation kinetics are presented to attain a universal scaling relationship for multivalent ion transport in polymers via metal-ligand coordination. [Preview Abstract] |
Monday, March 13, 2017 3:54PM - 4:06PM |
C9.00006: Direct Imaging of the Electrochemical Polymerization of Polythiophenes by In-Situ Transmission Electron Microscopy David Martin, Jinglin Liu, Bin Wei, Chin-Chen Kuo, Anirhudda Dutta, Vivek Subramanian Functionalized poly(thiophenes) such as poly(3,4-ethylene dioxythiophene) (PEDOT) are of considerable interest for a wide variety of applications including biomedical devices for interfacing electronic components with living tissue. The electrochemical deposition process involves oxidative polymerization of an aqueous EDOT monomer solution, resulting in precipitation of PEDOT onto a solid electrode as the reaction continues. The detailed mechanisms of this process have remained obscure, since it is experimentally difficult to determine local, high resolution information about the transition from the liquid precursor monomer solution to the solid polymer product. Here, we discuss recent results from our laboratory using low dose, in-situ transmission electron microscopy with an electrochemical liquid flow cell. This method has allowed us to quantify the nucleation and growth of droplets of PEDOT oligomers and polymers with current during the electrochemical polymerization and solidification process. Our ongoing efforts are focused on understanding the influence of systematic variations in the composition of the reaction medium, particularly the role of additives such as macromolecular counterions, gels, and solid particles. [Preview Abstract] |
Monday, March 13, 2017 4:06PM - 4:18PM |
C9.00007: Role of monomer sequence and backbone chemistry in polypeptoid copolymers for marine antifouling coatings Anastasia Patterson, Brandon Wenning, Georgios Rizis, David Calabrese, John Finlay, Sofia Franco, Anthony Clare, Edward Kramer, Christopher Ober, Rachel Segalman The design rules elucidated in this work suggest that antifouling coatings bearing pendant peptoid side chains perform better overall in marine fouling tests than those with peptide side chains, with extremely low attachment of \emph{N. incerta} and high removal of \emph{U. linza}. This difference in performance is likely due to the lack of a hydrogen bond donor in the peptoid backbone. Furthermore, we show that the bulk polymer material of these hierarchical coatings (based on PEO or PDMS) plays a key role in determining both surface presentation and fouling release performance. We demonstrate these trends utilizing a modular coating based on a triblock copolymer consisting of polystyrene and a vinyl-containing midblock, to which sequence-defined pendant oligomers (peptides or peptoids with sequences of oligo-PEO and fluoroalkyl groups) are attached via thiol--ene ``click'' chemistry. Surface presentation was analyzed with X-ray photoelectron spectroscopy and captive bubble water contact angle, and antifouling performance was evaluated with attachment and removal bioassays of the marine macroalga \emph{U. linza} and diatom \emph{N. incerta}. [Preview Abstract] |
Monday, March 13, 2017 4:18PM - 4:30PM |
C9.00008: Reduced domain size and interfacial width in nanofilled block copolymer films by direct immersion annealing Alamgir Karim, Melanie Longanecker, Andrey Dobrynin, Sushil Satija, Joona Bang Most functional applications of nanofilled block copolymers (BCP) generally require a high loading of nanoparticles, which is difficult to achieve due to particle aggregation, slow kinetics of ordering, and disruption of block copolymer order. We demonstrate direct immersion annealing (DIA) as a promising directed self-assembly (DSA) method to overcome these problems. DIA is shown to fully order highly filled (Au-PSrPMMA nanoparticles) lamellar poly(styrene-b-methyl methacrylate) (PS-PMMA) BCP films, whose lamellar ordering is practically unimpeded by filler loading. Neutron reflection (NR) further confirms that DIA sharpens the interfacial width between PS-PMMA domains. In situ NR studies further reveal that DIA predominantly induced film ordering in a 5 mass percent anisotropic organoclay (C93A) filled PS-PMMA film in less than 30 s. In contrast, identical C93A nanofilled PS-PMMA films that were thermally annealed (19h at 160C) only exhibit partial ordering near the free surface. DIA films also exhibit notably reduced domain soacing, resulting in 2 times the number of BCP domains. [Preview Abstract] |
Monday, March 13, 2017 4:30PM - 4:42PM |
C9.00009: Patchy Particles of Block Copolymers from Interface-Engineered Emulsions Kang Hee Ku, YongJoo Kim, Gi-Ra Yi, Yeon Sik Jung, Bumjoon Kim A simple method for creating soft patchy particles with a variety of three-dimensional shapes has been developed through the evaporation-induced assembly of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) in an oil-in-water emulsion. Depending on the particle volume, a series of patchy particles in the shapes of snowmen, dumbbells, triangles, tetrahedra, and raspberry can be prepared, which are then precisely tuned by modulating the interfacial interaction at the particle/water interface using a mixture of two different surfactants. Moreover, for a given interfacial interaction, the stretching penalty of the BCPs in the patchy particles can be systematically controlled by adding P4VP homopolymers, which decreases the number of patches of soft particles from multiple patches to a single patch but increases the size of the patch. Calculations based on the strong segregation theory supported the experimental observation of various soft patchy particles and identified the underlying principles of their formation with tunable 3D structures. [Preview Abstract] |
Monday, March 13, 2017 4:42PM - 4:54PM |
C9.00010: Control of Macromolecular Architectures for Renewable Polymers: Case Studies. Chuanbing Tang The development of sustainable polymers from nature biomass is growing, but facing fierce competition from existing petrochemical-based counterparts. Controlling macromolecular architectures to maximize the properties of renewable polymers is a desirable approach to gain advantages. Given the complexity of biomass, there needs special consideration other than traditional design. In the presentation, I will talk about a few case studies on how macromolecular architectures could tune the properties of sustainable bioplastics and elastomers from renewable biomass such as resin acids (natural rosin) and plant oils. [Preview Abstract] |
Monday, March 13, 2017 4:54PM - 5:06PM |
C9.00011: Biodegradability of poly(butylene succinate-co-butylene adipate) (PBSA) controlled by temperature during the dried-gel process Hana Yamazaki, Tomoki Maeda, Atsushi Hotta Currently there is a growing interest in biodegradable plastics that can be readily degraded into H$_{\mathrm{2}}$O and CO$_{\mathrm{2}}$. Among them, poly(butylene succinate-co-butylene adipate)(PBSA) is one of the mechanically attractive materials that can be biodegraded by surrounding water molecules and microorganisms after the disposal of the plastics. In order to expand the use of PBSA, the proper and effective control of the biodegradability of PBSA should be realized. In this work, the dried-gel process of the PBSA was carefully studied considering the temperature of the process. Three different types of dried PBSA gels were prepared at three different gel-process temperatures. From the biodegradability testing by immersing the PBSA samples in NaOH aq., it was found that the percentage of the weight loss of the PBSA was increased, indicating that the biodegradability was enhanced as the gel preparation temperature became lower. In fact, smaller spherocrystals were observed in PBSA dried at cooler temperature, studied by the scanning electron microscopy (SEM). It was therefore concluded that the microstructures of PBSA could be well controlled by changing the gel preparation temperatures for the precise control of the biodegradability of PBSA. [Preview Abstract] |
Monday, March 13, 2017 5:06PM - 5:18PM |
C9.00012: Solution Exchange Lithography: A Versatile Tool for Sequential Surface Engineering Christian Pester, Kaila Mattson, David Bothman, Daniel Klinger, Kenneth Lee, Emre Discekici, Benjaporn Narupai, Craig Hawker The covalent attachment of polymers has emerged as a viable strategy for the preparation of multi-functional surfaces. Patterned, surface-grafted polymer brushes provide spatial control over wetting, mechanical, biological or electronic properties, and allow fabrication of `intelligent' substrates which selectively adapt to their environment. However, the route towards patterned polymer brush surfaces often remains challenging, creating a demand for more efficient and less complicated fabrication strategies. We describe the design and application of a novel experimental setup to combine light-mediated and flow chemistry for the fabrication of hierarchical surface-grafted polymer brushes. Using light-mediated, surface initiated controlled radical polymerization and post-functionalization via well-established, and highly efficient chemistries, polymer brush films of previously unimaginable complexity are now shown to be accessible. This methodology allows full flexibility to exchange both lithographic photomasks and chemical environments in-situ, readily affording multidimensional thin film architectures, all from uniformly functionalized substrates. [Preview Abstract] |
Monday, March 13, 2017 5:18PM - 5:30PM |
C9.00013: Evaporation-Rate-Dependent Morphological Evolution of Uniform-Sized Block Copolymer Particles Jaeman Shin, YongJoo Kim, Bumjoon Kim Block copolymer (BCP) self-assembly in evaporative emulsions can lead to non-spherical particle with unique nanostructure when the emulsion surface is neutralized to the surrounding. In this work, we demonstrate that kinetic parameter, solvent evaporation rate, can also control the shape of the polystyrene-$b$-polybutadiene (PS-$b$-PB) BCP particle. A distinct morphological transition of the particles from ellipsoids with striped lamellae to onion-like spheres was observed as the evaporation rate was decreased, and the critical evaporation rate for the transition was dependent on the molecular weights of PS-$b$-PB. Furthermore, the evaporation rate was found to affect the self-assembly orientation of BCPs at the particle surface, which eventually determined the final structure of BCP particles. In the case of rapid evaporation, large differences between the toluene diffusivity in PS and in PB induced BCP to align perpendicular to the particle surface. By contrast, thermodynamic effects lead BCP to assemble parallel to the particle surface at slow evaporation. [Preview Abstract] |
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