Structure and permeation of organic-inorganic hybrid membranes composed of poly(vinyl alcohol) and polysilisesquioxane

Organic-inorganic hybrid membranes with high separation performance were prepared by the incorporation of polysilisesquioxane (PSS) into a poly(vinyl alcohol) (PVA) matrix in order to solve the trade-off relationship between the selectivity and permeability of PVA membranes. The incorporation of the PSS resulted in a change in the physical and chemical structure of the hybrid membranes. The crystalline region in the hybrid membranes decreased with increasing PSS content. The hydrophilicity of the hybrid membranes increased when the PSS content is below 3 wt%, and then decreased. Silica particles formed on the surface and in the interior of the hybrid membranes due to the PSS conglomeration, and the surface roughness of the hybrid membranes increased linearly with increasing PSS content. The trade-off between permeability and selectivity was successfully solved using the hybrid membranes in pervaporation dehydration of tetrahydrofuran. The permselectivity and flux of the hybrid membranes increased simultaneously when the PSS content was below 2 wt%, whereas the permselectivity decreased when the PSS content was above 2 wt%. The hybrid membrane containing 2 wt% PSS had the highest separation factor of 1810.