Characterization and permeation performance of novel organic-inorganic hybrid membranes of poly(vinyl alcohol)/1,2-bis(triethoxysilyl)ethane.

Bis(trialkylsilyl) precursor was used to modify polymer membranes for the first time. Novel organic-inorganic hybrid membranes of poly(vinyl alcohol) (PVA)/1,2-bis(triethoxysilyl)ethane (BTEE) were prepared through a sol-gel method for pervaporation dehydration of ethanol. The permeability and selectivity of the membranes were improved simultaneously. The physicochemical properties of the hybrid membranes were investigated. With increasing BTEE content, the amorphous region in the hybrid membranes increased and became more compact. Phase separation took place in the hybrid membranes containing abundant BTEE, and silica particles distributed in the PVA matrix homogeneously. Compared to PVA membranes, the hybrid membranes exhibit high thermal stability and improved separation performances. Silica-hybrids reduced significantly the swelling of PVA membranes in an aqueous solution. The Flory-Huggins interaction parameter of water with membranes chi13 increased with increasing BTEE content, whereas that of ethanol with membranes chi23 decreased. Diffusion behavior of water and ethanol through the membranes were analyzed using the Maxwell-Stefan equation. When BTEE content was below 6 wt%, diffusion coefficient of water D13 increased remarkably and that of ethanol D23 decreased slightly.