Field-Theoretic Polymer Simulations: Fundamentals and Applications

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TECHNICAL SUMMARY:This award supports computational and theoretical research and education in the area of polymer simulation. This project will build on the recent development by the PI and co-workers of the "field-theoretic simulation" (FTS) method, enabling numerical investigations of field theory models of polymers, complex fluids, and soft materials without resorting to the mean-field approximation. The proposed research encompasses both fundamental and applied components.. Foundations and extensions of the FTS method. This research thrust will include development of improved numerical schemes for time integration of the stochastic "complex Langevin" equations used to implement potential field updates. We also propose to develop a new "ground state-FTS" technique that should dramatically accelerate simulations of strongly overlapping polymer solutions (neutral and charged) in the semi-dilute and concentrated regimes.. Numerical renormalization group theory. We propose to implement pseudospectral numerical RG transformations in tandem with complex Langevin simulations of polymer field theories. This will facilitate the isolation of lattice cutoff effects and enable systematic coarse-graining of polymer solution models. The PI envisions applications to block copolymers in selective solvents.. Hybrid particle-field simulations. We propose to develop a new class of simulations for treating nanoparticles or colloids embedded in structured polymer fluids. The particles are treated as "cavities" in the fluid fields and the particle coordinates are retained along with the fluid field variables.. Defects in confined copolymer films. Translational and bond-orientational order will be examined in FTS simulations of block copolymer films with perimeter boundary conditions. The results will be used to assess the efficacy of grapho-epitaxy for creating defect-free copolymer films that can be used in ultra-high density patterning of advanced electronic, optical, and magnetic devices. The proposed research will closely couple with an experimental program underway in the laboratory of Edward J. Kramer at UCSB.The PI will continue in his tradition of effective graduate and post-doctoral training in theoretical and computational polymer science. A particular focus will be to expose students and post-docs with classical physics training to broader soft materials/polymer science disciplines through a close coupling with experimental groups at UCSB in chemical engineering, materials, and chemistry. The fundamental understanding gained under the proposed project will be further leveraged through the Complex Fluids Design Consortium (CFDC) at UCSB, an industry-national lab-academic partnership that is addressing the computational design of commercial polymer and complex fluid formulations.NON-TECHNICAL SUMMARY:This award supports computational and theoretical research and education in the area of polymer science using computers to simulate polymer materials and polymer-related phenomena. The PI plans to continue his work on fundamental theoretical advances and new algorithms aimed at extending a simulation method he developed and at developing new simulation methods for inhomogeneous polymer materials, complex fluids, and soft materials. These methods are needed to handle essential physics that arises across diverse length and time scales in these materials and often makes reliable computer simulation difficult. In an effort coupled to experiment, the PI plans to apply these newly developed advanced simulation methods to thin films of block copolymers and to investigate a promising experimental technique for creating nearly perfect copolymer films that can be used as a template to synthesize inorganic nanowires, nanodots, and other nanoscale structures. The PI will continue in his tradition of effective graduate and post-doctoral training in theoretical and computational polymer science. A particular focus will be to expose students and post-docs with classical physics training to broader soft materials/polymer science disciplines through a close coupling with experimental groups at UCSB in chemical engineering, materials, and chemistry. The fundamental understanding gained under the proposed project will be further leveraged through the Complex Fluids Design Consortium (CFDC) at UCSB, an industry-national lab-academic partnership that is addressing the computational design of commercial polymer and complex fluid formulations.