Influence of in situ silica gel supporting on the pore structure stability of polyacrylonitrile-based thermally crosslinked organic solvent nanofiltration membrane

In this work, in situ sol–gel strategy was used to introduce silica gel in polyacrylonitrile (PAN) membrane pores, by which the pore structure of organic solvent nanofiltration (OSN) membrane prepared with thermal crosslinking was maintained well. The chemical structure, microstructure and morphology changes of membrane during sol–gel and thermal crosslinking were systematically studied by FTIR, XPS, XRD and SEM. Benefitting from the introduction of silica gel, the fusion of membrane pore structure during thermal crosslinking was effectively inhibited by supporting the pore with silica gel. Therefore, the permeances of the thermally crosslinked membranes supported by in situ silica gel were greatly improved. Furthermore, the thermally crosslinked membrane showed excellent stability of OSN performance due to the generated ladder structure of membrane during thermal crosslinking. This work showed that in situ silica gel supporting is a promising strategy to stabilize the pore structure of PAN membrane during thermal crosslinking.