Insight of chitooligosaccharides diffusion within polymeric membranes using molecular dynamic simulation

Abstract

The membrane separation technology with the advantage of cost-benefit, energy-efficient and ease to scale up, is promising to realize the industrialized separation of chitooligosaccharides (COS) to meet the industrial demands. While COS with different degree of polymerization (DP) have similar molecular size and physicochemical properties which hinders the precise separation of COS by the commercial membranes. Herein, molecular dynamics simulations were performed to explore the diffusion behavior of COS within PEEK, PES, PSF, PVDF and PPTA membranes, to provide a theoretical basis for the screening and development of novel polymeric membrane materials for precise separation of COS. The interaction among the COS, water, and the polymer chains were investigated by calculating diffusion coefficient, interaction energy, hydrogen bonding and radial distribution function. And the diffusion process of the COS within the five polymeric membranes was investigated. Results showed that the diffusion behavior of the COS within the polymeric membranes depended on the interactions among the polymer chain, COS and water, which determined by the DP of COS and the structural properties of the polymer chain. Compared with other four kinds of materials, the interaction between PPTA chain and COS molecules repressed the decline trend of the difference between the diffusion coefficients of COS with adjacent DP as the DP of COS increased, making PPTA the most beneficial to the precise separation of the COS with different DP.