(189o) Molecular Dynamics Simulation of Modified Nafion 117 Based Anion Exchange Membrane Fuel Cell: Transport and Nanophase-Segregated Structure Properties

Caliendo, C. Jr., Georgia Institute of Technology
Jang, S. S., Georgia Institute of Technology
In this research, we investigate the effect of structural variation of Nafion 117 on the nanophase-segregation and transport properties using molecular modeling approach. In this study we replace the sulfate group of nafion117 with two different phosphate groups, and characterize its effect on nanophase-segregated structure and transport of water/protons at 80oC with various water contents. The two groups that will be tested are: changing the entire tail group to a polyvinyl phosphate, and changing the tail group to a difluoromethandiphosphonic acid. This will be done by simulating the new molecular structures using molecular dynamic simulations at 80oC under isobaric conditions using LAMMPS. Dreiding force field will be partially modified to handle perfluorocarbon compounds, water, and hydronium. The equations of motion will be integrated using Verlet algorithm with a 1-fs time step, and the PPPM method to evaluate the electrostatic interactions. After an equilibration cycle, each system will then be simulated for an extra 2 ns to sample structures for statistical treatment. By simulating the proton conductivity of these molecules we seek to understand the relationship among underlying polar groups, nanophase-segregated structure, and transport which would serve in designing new polymer electrolyte membranes.