Molecular Simulations of Phase Behavior for Polymer Blends and Block Polymers

Abstract

The wide variety of phase behavior associated with polymer mixtures and block polymers enables unprecedented opportunities in developing novel polymeric materials with desired properties. However, the molecular design space of multi-component polymer systems is now so vast that guidance from theory and modeling is essential. The greatest challenge of predictive materials design is the lack of accurate and precise simulation methods in computing the phase diagram of polymer systems, due primarily to difficulties in (i) transferring polymer molecules between condensed phases and (ii) the sensitivity of phase diagram with respect to the interaction parameters used in the simulations. The overarching goal of this thesis is to address the above two problems. In this thesis, advanced sampling techniques of Monte Carlo simulations and accurate molecular models were developed to allow for the accurate and precise calculation of the mixing thermodynamics for binary mixtures. Furthermore, a case study of predictive materials design is presented, where molecular dynamics simulations were employed to explore the phase diagram of block oligomers with various chain lengths, volume fractions, and chain architectures, and thus, to guide the experimental synthesis for molecules with desired microphase morphologies. The work in this thesis lays a solid foundation for predictive materials discoveries using molecular simulations.