Molecular Design of Sulfonated Triblock Copolymer Permselective Membranes; Final rept. 12 Jul 2007-2008

摘要

Search for novel polymeric electrolyte membranes (PEM) suitable as permselective diffusion barriers is one of the key problems in engineering new protective materials. The goal of the project was to get a better understanding of the physical and chemical factors governing sorption and permeability of phosphoorganic agents in PEM made of sulfonated triblock copolymers of styrene and lower olefins by means of multiscale molecular simulations. These materials are of special interest to the Army as low-cost substitutes of expensive Nafion- type membranes. Concentrating on sulfonated polystyrene containing block- copolymers, we developed a hierarchical multiscale methodology for computational studies of the membrane morphology at environmental conditions, and the membrane sorption and transport properties with respect to water and nerve gas simulant dimethylmethylphosphonate (DMMP). The methods developed include: (1) quantum mechanical ab-initio calculations of specific interactions of DMMP and water with the membrane fragments, (2) atomistic molecular dynamic simulations of membrane solvation in water-DPPM mixture with different counterions, (3) large-scale molecular dynamic simulations of membrane segregation and mobilities of chemicals, and (4) dissipative particle dynamics simulations of mesoscopic morphologies in solvatedmembranes of different composition. The molecular simulation studies were performed in concert with the experimental work at Natick Soldier, RDEC, Natick, MA.