Swelling and sorption behaviour of PVA and PVA/silica nanocomposite membrane at different silica loadings

Abstract

Intercalation of nanomaterial with a polymer is an intriguing approach for modifying the microstructure of polymer to improve the swelling property, performance, and selectivity of the membrane. The effect of sorption and swelling on membrane selectivity of organic-inorganic polyvinyl alcohol/silica (PVA/SiO₂) membranes with a different weight percentage of silica has been investigated using propanol/water, isopropanol/water, and butanol/water mixture. The PVA composite membrane is prepared using solution casting method, and sol-gel derived route using tetraethoxysilane (TEOS) as the precursor material for silica and PVA as a polymer. Swelling experiment results show an inverse relationship between the degree of swelling and the silica concentration due to the formation of a rigid structure with increase in weight of the nanomaterial. Dense structure results in less free volume and decreases the amount of absorbed liquid in the polymer at a lower concentration of nanoparticles. The result is also modeled using Flory Huggins parameter, and the similar trend was observed as for the experimental value for the degree of swelling.