Structural characteristics and transport behavior of triptycene-based PIMs membranes: A combination study using ab initio calculation and molecular simulations

Abstract

The combination of ab initio calculation, molecular dynamics (MD) and Monte Carlo (MC) simulations was used to investigate the structural characteristics and transport behavior of PIM-Trip-TB and KAUST-PI-1 membranes. The PIM-Trip-TB and KAUST-PI-1 membranes are composed of rigid bridged Triptycene (Trip) units and are potential candidate membranes in gas separation processes. The effect of the Triptycene units on the membrane structure and gas transport behavior was analyzed in this study. Compared to the PIM-PI-1 membrane, which consists of the less rigid spirobisindane (SBI) units, the PIM-Trip-TB and KAUST-PI-1 membranes revealed larger surface areas, higher fraction free volume values, and narrower distributions of dihedral angles. Furthermore, the membrane transport properties were evaluated by investigating the adsorption isotherm, self-diffusion behavior, and selectivity of various gases on the membranes. The simulation results agreed well with experimental data, demonstrating that the combination of ab initio calculation, MD and MC simulations is a reliable tool for the characterization of membranes.