Molecular Dynamics Simulation for Separation Performance of PDMS/Fluorosilane Membrane with Different Mass Ratios in Acetone–Water Mixture

Abstract

AbstractPolydimethylsiloxane (PDMS) membrane in suitable‐fluorinated level have excellent pervaporation performance as well as antibiological contamination performance. The pervaporation membranes with different PDMS/fluorosilane mass ratios, the adsorption and dissolution behaviors of acetone molecules on the membrane surface, as well as the diffusion and permeation behaviors in the membranes are studied by all‐atom molecular dynamics simulation (AAMDS). The results show that when the mass ratio of PDMS/fluorosilane is 100/20, the surface solubility of acetone is 11.711 (J cm−3)0.5, and the interfacial interaction is −16897.0415 kcal mol−1, both of which are the highest. The results of wide‐angle X‐ray diffraction (WAXD) showed that there are amorphous regions in the membranes suitable for acetone penetration. The maximum chain spacing of the PDMS/fluorosilane(100/20)_membranes is 10.8482 Å, and the free volume fraction (FFV) is 3.03%, both of which are the largest. The change rate of long‐term mean square displacement (MSD) in PDMS/fluorosilane(100/20)_Membrane with time is 0.45269. The Young's modulus E, shear modulus G, volume modulus K, and Poisson's ratio ν of PDMS/fluorosilane(100/20)_Membrane are 0.3249, 0.4061, 0.0492 GPa and ‐0.5999, respectively. The elasticity of the membrane enhances the diffusion behavior of acetone molecules, and the self‐diffusion coefficient of acetone in the membrane is 0.07545 Å2 ps−1.