Microstructure-related performances of poly(vinyl alcohol)-silica hybrid membranes: a molecular dynamics simulation study

Abstract

Molecular dynamics (MD) simulations were used to reveal the relationship between the microstructure and performance of PVA–silica hybrid membranes from the hybridization of silanols, R–Si(OH)₃. We first studied the PVA membranes hybridized by silanols with the linear alkyl group of –C_nH_2n+1 to investigate the effect of their size on the microstructure and properties of the hybrid membranes, then studied hybridization of H₂N(CH₂)₃–Si(OH)₃ (APTS) from the hydrolysis of APTEOS. Silica hybridization reduced the mobility of PVA chains remarkably, raised the amorphous region in the PVA matrix, and adjusted the membrane microstructure. Group R in the silanol R–Si(OH)₃ has a prodigious effect on the microstructure and performances of the hybrid membranes. Small free volume cavities decreased, and the interchain spacing of PVA chains and big cavities increased with increasing size of group R. Furthermore, MD simulations revealed a relationship between the microstructure and performances of the PVA/APTS hybrid membranes. The results could provide guidance for designing novel functional silica-based hybrid membranes.