Influences of van der waals volume of substitute groups on CO₂ permselectivity of polyimide‐A molecular simulation study

Abstract

Polyimide (PI) as a typical glassy polymer material was investigated by molecular simulation to reveal the relationship between polymer molecular structure and its gas separation properties. The influences of van der waals volume (V w ) on CO 2 permselectivity of PI polymers (with four kinds of backbone substitute groups and a series of side substitute groups from small to large volume) and V w was proposed as an intermediate to establish the relationship between the substitute group and permselectivity. The results show that the CO 2 permeability (P) simply increases and CO 2 /N 2 selectivity (S) decreases with the increasing V w of side substitute groups. The linear fitline of P-V w is much suitable to describe and predict the effect of the increasing V w of side substitute group on improving permeability by analyzing the experimental and calculated CO 2 permeability. The increasing V w of backbone substitute group can slow down the increasing of CO 2 permeability, but result in the decreasing first and then recovering to the original level.

Structure-Gas Barrier Property Relationship in a Novel Polyimide Containing Naphthalene and Amide Groups: Evaluation by Experiments and Simulations

“…This provides a unique opportunity to study the barrier mechanism of polymers at the molecular level [ 33 , 34 , 35 , 36 ]. The parameters related to the barrier properties, such as the size and distribution of free volume, penetrant trajectories, diffusion coefficient, and solubility coefficient can be obtained by molecular simulation [ 37 , 38 , 39 , 40 ].…”