Theory of Polymer Crystallization

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TECHNICAL SUMMARYThis award supports theoretical research and education with an aim to develop theories of polymer crystallization and directed polymer assembly, by employing simulation techniques and statistical mechanics. Crystallization of polymers from solutions and melts is one of the longstanding research areas in polymer science. A fundamental understanding of how polymer chains organize into hierarchical structures remains elusive. The conformational entropy of flexible polymer molecules makes the crystallization phenomenon of polymers distinct from ordering of small molecular systems. The same entropic aspects of polymers are manifest in various directed assemblies of diblock copolymers and biological polymers. Previous work by the PI to address the effects of the conformational entropy has resulted in novel ways of interpreting the rich phenomenology of polymer crystallization. These are complementary to the traditional arguments in the literature, which essentially ignore the conformational entropy. This award supports research that will build on recent new ideas to explore several related ordering phenomena of polymers. Specifically, (a) lamellar morphology in polymeric spherulites, (b) kinetics of growth fronts in polymer solutions and melts, and (c) directed assembly of polymers will be addressed. This project is aimed at building new conceptual models and discovering new laws of polymer assembly. The proposed theoretical work complements experimental investigations being actively pursued in laboratories worldwide.NON-TECHNICAL SUMMARYThis award supports integrated computational and theoretical research and education aimed to understand how, polymers, large long-chain molecules made of many smaller repeating molecular units, organize into ordered states. Of particular interest is how they crystallize. The many ways long-chain molecules can twist and bend makes the crystallization process of polymers distinct from that of many other materials. The PI will use computer simulations and build on previous work, his own and that of others, to develop an understanding of polymer crystallization. The results of this research may have impact in numerous applied areas such as polymer processing, the fabrication of polymeric materials down to scales some ten thousand times smaller than a human hair, and the process by which molecules and other 'building blocks' of materials assemble themselves to form biological structures and living matter. Many, if not most, modern materials are made from processed semicrystalline polymers, which are the subjects of the proposed theoretical and modeling investigation. A fundamental understanding of the behavior of this important class of materials will help to design and process novel polymeric materials with enhanced benefits to our society. This activity provides support for training of graduate students in this challenging research area and the workforce of the twenty first century.