Plasma modification of substrate with poly(methylhydrosiloxane) for enhancing the interfacial stability of PDMS/PAN composite membrane

Abstract

This paper described a facile approach to improve the interfacial stability of poly(dimethylsiloxane)/polyacrylonitrile (PDMS/PAN) composite membranes mediated by poly(methylhydrosiloxane) (PMHS). The surface of PAN substrates was modified with PMHS by plasma treatment. The chemical structure and surface morphology of modified PAN substrates were characterized by ATR-IR, XPS, SEM, AFM and CA. The interfacial stability of composite membranes was estimated using the crosshatch tape adhesion test and the swelling experiment. The results showed that the composite membranes supported by modified PAN substrates exhibited high interfacial adhesion and the corresponding PDMS separation layer displayed quite low swelling degrees in toluene and n-heptane, due to the enhanced interfacial interaction. Such enhancement was produced by the stronger mechanical interlocking (increased surface roughness of substrate) and the presence of chemical bonding between PDMS layer and modified PAN substrate. Furthermore, these composite membranes showed good pervaporation performance with a separation factor about 4.2 and a high flux above 9.5kgm−2h−1 in the separation of azeotropic methanol/toluene mixture at 30°C. This work demonstrated that plasma-induced immobilization of PMHS on PAN substrate was an efficient way to improve the interfacial stability of PDMS/PAN composite membrane without sacrifice of its pervaporation performance.