Polymer rigidity effect on gas transport behavior: gas molecule diffusion through polymer membrane

Gas separation technology based on polymeric membranes is currently highlighted due to emerging highly porous polymer materials with high gas transport performance. Key factor for the performance improvement is believed to give rigidity into polymer main-chain which can increase porosity (i.e., free volume) inside. However, it is still unclear how rigidity affects the free volume and also how the change in the free volume can improve gas transport property. Going one step further from the conventional insight about the relationship between the amount of free volume and gas permeability collectively analyzed from the bulk polymer properties, we turned our focus into the movement of each gas molecule through polymer matrix, defined as diffusion. In this presentation, we will demonstrate how rigidity improves the free volume morphology to become preferable for gas molecules diffusion, and also suggest in which way the gas molecules diffuse through the free volume, using molecular simulation tools.