Molecular dynamics simulation and experimental verification of influence of crosslinking reaction process parameters on oxygen permeability of PDMS membranes

Abstract

Sufficient oxygen permeability of the substrate is the key to ensuring the reliability of the Continuous Liquid Interface Production process. Polydimethylsiloxane (PDMS), as a cost-effective material with good gas permeability, holds potential for applications as oxygen-permeable windows in constrained substrates. Therefore, it is of great significance to investigate how to enhance the oxygen permeability of PDMS. In this study, the program code for the crosslinking reaction between the prepolymer and curing agent was developed. Molecular dynamics simulations were employed to investigate the effects of the process parameters on the diffusion coefficient of oxygen. Validation experiments were conducted by measuring the oxygen permeability of the substrate. The research findings reveal that process parameters, including crosslinking time, crosslinking temperature, and the mass ratio of prepolymers to curing agents, influence the diffusion coefficient of oxygen in PDMS membranes. Increasing the crosslinking time leads to an increase in the number of crosslinking points, hindering polymer chain mobility and limiting the increase in free volume, thereby decreasing the oxygen diffusion coefficient. An optimal crosslinking temperature of 348 K enhances the probability of jump channel formation between cavities, resulting in the maximum oxygen diffusion coefficient. The oxygen diffusion coefficient of PDMS membranes increases with rising mass ratio.