Transport Behavior of Oxygen and Nitrogen through Organasilicon-Containing Polystyrenes by Molecular Simulation

Abstract

Molecular dynamics (MD) simulations have been used to study the transport properties of oxygen and nitrogen in the para-substituted polystyrenes which possess one to four Si atoms in each substituent. The Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field was used to construct the polymers. Diffusion coefficients were obtained from molecular dynamics (NVT ensemble) with up to 3 ns simulation times. After molecular dynamic simulation, the trajectories of the small molecules in the polymer matrix were obtained. Then diffusion coefficients have been calculated from the Einstein relationship revealing a considerable agreement between the simulated and the experimental data. And solubility coefficients have been calculated by the Grand Canonical Monte Carlo (GCMC) method. The solubility of oxygen increased with increasing Si content in the polymer membrane. The para-substituted polystyrenes with a branched substituent at the alpha-position showed higher permeability than those of the nonbranched ones. The higher the glass transition temperature (T(g)) of the membrane, the larger the diffusion coefficients of oxygen and nitrogen obtained.

Elucidation on the Effect of Operating Temperature to the Transport Properties of Polymeric Membrane Using Molecular Simulation Tool

“…In current work, the diffusivity of gas penetrants has been determined adopting the means of molecular positioning theory, or more commonly known as the Einstein relationship [18][19][20][21][22][23][24]. In Einstein correlation, he related the self-diffusion coefficient of gas particles i, D i to the mean square displacement (MSD) as a function of observation time, such as that presented in (1), through the assumption of particle random walk [25].…”

Molecular simulation study of penetrant gas transport properties into the pure and nanosized silica particles filled polysulfone membranes

“…In MD simulation, the diffusion coefficient for the penetrant is calculated by means of the Einstein relationship [18,55,66,[68][69][70].…”

Diffusion of CO2Molecules in Polyethylene Terephthalate/Polylactide Blends Estimated by Molecular Dynamics Simulations

“…The criterion for a model system reaching the normal diffusion regime is the slope of log(MSD) vs log(t) approaches unity. 32 From Figure 5, the slope of the log(MSD) vs log(t) curve increases approximately to unity after long time MD simulation over the entire composition range of PET/PLA blends. This result confirms the feasibility of MD approach to reach the normal diffusion regime of CO 2 in PET/PLA blends.…”