Field-theoretic simulations with excluded volume correlations

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Nontechnical SummaryThis award supports development of a theoretical and computational framework for understanding the thermodynamics of polymer nanocomposites, a class of materials where small, typically inorganic nanoparticles are dispersed in a polymer matrix. Polymer nanocomposites are explored for a diverse set of applications ranging from lightweight protective materials to plastic membranes with tunable electronic properties, yet there are relatively few modeling techniques capable of accurately predicting their equilibrium structure and properties. This research will help with development of a family of new modeling techniques capable of predicting how polymer nanocomposites will assemble on the molecular level. This could aid in the design of conductive plastic materials, polymers with tunable optical properties, and mechanically robust polymer nanocomposites. This award will support training of graduate students in molecular modeling techniques and modern polymer science. The students will interact with experimental groups in Chemistry, Materials Science, and Chemical and Biomolecular Engineering Departments at the University of Pennsylvania. The developed simulation codes will be made publicly available. This will facilitate the broader application of new modeling techniques.Technical SummaryThis award supports the development of field theoretic simulation framework for a class of problems where excluded volume correlations become important. In traditional implementations of polymer field theory, the constituents of the model are taken as either point particles or infinitely thin threads with a contact repulsion. However, in a number of technologically important materials ranging from polymer nanocomposites to polyelectrolytes exposed to multivalent ions, a point-particle description is invalid. The goal of this funded research is to extend the field theoretic simulations framework to study: (i) the distribution of both spherical and anisotropic nanoparticles in a polymer matrix, including phase separated polymer blends and block copolymers; (ii) homogeneously grafted nanoparticles, where the grafting sites are uniformly distributed on the nanoparticle surface; and (iii) charged polymeric systems in the presence of multivalent ions. The results the field theoretical calculations will be compared with particle-based simulations and with existing experiments.