Molecular dynamics and Monte Carlo simulation of the structural properties, diffusion and adsorption of poly (amide-6-b-ethylene oxide)/Faujasite mixed matrix membranes

Abstract

Molecular simulation has been undertaken to study the structural and transport properties of Poly (amide-6-b-ethylene oxide) (PEBA 1657)/Faujasite (FAU) mixed matrix membranes. Membranes were built with different amounts of FAU nanomaterials to investigate the influence of nanomaterial content on the membrane performances. Structural characterizations such as ractional free volume (FFV), radial distribution function (RDF), wide angle XRD (WAXD) and glass transition temperature were done on the simulated membrane cells to study their structural properties. Also, by using MSD and adsorption isotherms, diffusivity and selectivity of these membranes were measured, respectively. The two main transport factors (permeability and permselectivity) were examined using calculated diffusivity and solubility, and the membrane properties were investigated at two different operating temperatures (298 K, 318 K). Results show that by increasing the nanomaterials content, structural properties improve and transport properties increase which is due to the increase of the pathways for penetrant molecules to move through the membranes. Compared to the published results, the current simulation study is more accurate in describing the structural and transport properties of PEBA/FAU mixed matrix membranes. It was found that increasing the FAU content from 0 to 20 wt% increased the permeability of the membrane to CO2, as well as the permselectivity for CO2/NO2 from 69.4 barrer to 89.23 barrer at 298 K. This change in FAU content also decreased the glass transition temperature from 212 K to 204.1 K.