Aquivion Ionomer in Mixed Alcohol-Water Solution: Insights from Multi-Scale Molecular Modeling

Short side-chain ionomers such as Aquivion are increasingly used in the fabrication of PEM fuel cells. Aquivion exhibits lower gas crossover, higher glass transition temperature, better mechanical stability, and higher conductivity compared to Nafion, their long side-chain relative. We performed atomistic molecular dynamic simulations of Aquivion at different water contents and varying proportions of iso-propanol and examined the structure and dynamics of the system. These simulations are accompanied with coarse-grained simulations to develop a coarse-grained model applicable to both long and short side-chain ionomers. The density of Aquivion and Nafion membranes from simulations is calculated and compared with that from experiment. The water network morphology is analyzed as a function of water content.