Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session X51: Using Polymer Sequence to Control Material PropertiesInvited
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Sponsoring Units: DPOLY DBIO Chair: Lisa Hall, Ohio State University Room: BCEC 253A |
Friday, March 8, 2019 8:00AM - 8:36AM |
X51.00001: Using PRISM theory and molecular simulations to understand the complex interplay of copolymer sequence and architecture on assembly in polymer solutions Invited Speaker: Arthi Jayaraman In this talk I will present our recent work using molecular dynamics (MD) simulations and PRISM theory aimed at understanding effects of non-linear polymer architecture and sequence on structure and thermodynamics within polymer solutions. I will focus on amphiphilic copolymer solutions and show how copolymer architecture (linear, bottle brush, cyclic), sequence (diblock, triblock) and composition impact assembled micelle structure (i.e. shape, size, aggregation number) and thermodynamics (i.e. critical micelle concentration, disorder to order transition). I will also discuss how we use PRISM theory and MD simulations in a synergistic and sequential manner to screen through this large polymer design space to achieve our desired structure and thermodynamics in these polymer solutions. |
Friday, March 8, 2019 8:36AM - 9:12AM |
X51.00002: Impact of Structural Correlation and Monomer Heterogeneity in the Phase Behavior of Soft Materials and Chromosomal DNA Invited Speaker: Andrew Spakowitz Polymer self-assembly plays a critical role in a range of soft-material applications and in the organization of chromosomal DNA in living cells. In many cases, the polymer chains are composed of incompatible monomers that are not regularly arranged along the chains. The resulting phase segregation exhibits considerable heterogeneity in the microstructures, and the size scale of these morphologies can be comparable to the statistical correlation that arises from the molecular rigidity of the polymer chains. To establish a predictive understanding of these effects, molecular models must retain sufficient detail to capture molecular elasticity and sequence heterogeneity. This talk highlights efforts to capture these effects using analytical theory and computational modeling. First, we demonstrate the impact of structural rigidity on the phase segregation of copolymer chain in the melt phase, resulting in non-universal phase phenomena due to the interplay of concentration fluctuations and structural correlation. We then demonstrate how these effects impact the phase behavior in statistical random copolymers and in heterogeneous copolymers based on chromosomal DNA properties. With these results, we demonstrate that the spatial segregation of DNA in living cells can be predicted using a heterogeneous copolymer model of microphase segregation. |
Friday, March 8, 2019 9:12AM - 9:48AM |
X51.00003: Molecular Engineering Complex Coacervate Materials Using Sequence Invited Speaker: Sarah Perry Polyelectrolyte complexation can be used in the self-assembly of a wide range of responsive, bioinspired soft materials. Material responses can include swelling and dissolution or liquid-to-solid transitions, which can be harnessed to facilitate encapsulation and the subsequent fabrication of functional materials. Drawing inspiration from proteins as sequence-controlled polymers, we utilize polypeptides as a model platform to study how the patterning or presentation of charges and other chemical functionalities affects the resulting self-assembly and material properties, including the ability to selectively uptake and stabilize globular proteins. Our experimental efforts are supported by the parallel development of computational approaches for modeling and predicting the phase behavior of patterned polymeric materials. The goal of this systematic investigation is the elucidation of molecular engineering design rules to facilitate the tailored creation of materials based on polyelectrolyte complexation that can both illuminate self-assembly phenomena found in nature, and find utility across a wide range of real-world applications. |
Friday, March 8, 2019 9:48AM - 10:24AM |
X51.00004: Sequence-controlled polymers: bridging the gap between biotic and abiotic macromolecules Invited Speaker: Jean-Francois Lutz Over the last decades, synthetic polymers and biological macromolecules have been studied by different scientific communities. Man-made plastics are obtained by simple one-pot polymerization methods and exhibit therefore non-uniform molecular structures. Consequently, molecular polydispersity shall be taken into account in synthetic polymer chemistry and physics. In contrast, biopolymers are produced by precisely-controlled biosynthesis and have perfectly-defined molecular structures. Thus, they exhibit folding and organization properties that are difficult to attain with conventional synthetic materials. Hence, biochemistry and biophysics are disciplines on their own. Yet, in the last few years, the traditional boundaries between biological and non-biological polymers tend to disappear. Due to recent progress in synthetic polymer chemistry, it is today possible to synthesize a wide variety of uniform synthetic polymers. In particular, significant advances have been reported for the synthesis of sequence-controlled polymers, which are man-made macromolecules with perfectly-controlled primary structures. This new class of synthetic polymers open up unprecedented possibilities for tuning structure/property relationships. However, the physical chemistry of these novel materials has been barely investigated to date. In this talk, I will highlight recent approaches developped in my laboratory for the synthesis of uniform sequence-defined polymers. Particular emphasis will be put on the design of abiotic information-containing macromolecules, which are new functional polymers inspired by nucleic acids. |
Friday, March 8, 2019 10:24AM - 11:00AM |
X51.00005: Segmented Ionenes: Precision within disperse structures yields interesting microstructures and stimuli-responsive behavior Invited Speaker: Matthew Green Ionenes are polymers containing a permanent charged group in the polymer backbone and are of interest because of their synthetic versatility, unique morphologies, and ionic nature. The charge placement and the spacing between the charge segments enable the polymer properties to be tuned from glassy solids to rubbery films to viscous liquids. The use of long, soft segment spacers between charges produces a class of polymer called segmented ionenes. When segmented ionenes are prepared with halide counterions (i.e., strong basicity) they form thermoplastic elastomers and microphase separate into microstructures wherein the ionic domains can form a continuous, percolated network at sufficient volume fractions. This talk will discuss recent efforts to utilize the synthetic versatility of this class of polymer to prepare percolated ionic domains in microphase separated polymers that display a range of thermomechanical properties. Furthermore, the combination of synthetic versatility and electrostatic interactions can be used to influence the dispersion of nanoparticles in a segmented ionene matrix as well as influence the nanoparticle solubility in specific microdomains. Finally, the response to external stimulus (e.g., electrical, mechanical) will be discussed and connected to varying chemistries and microstructural features of the polymers. |
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