(288e) Novel Polyimide Membranes and Their Modification for Pervaporation Applications
Membrane is one of the critical factors for the separation efficiency of the pervaporation technology. A desirable pervaporation membrane should possess high flux, superior separation factor, and long-term chemical and mechanical stability. Common hydrophilic polymeric membrane materials, such as polyvinyl alcohol, chitosan and sodium alginate etc., have been widely used for pervaporation dehydration because of their high selectivity towards water, but they generally suffer severe swelling in the aqueous solution, leading to the poor operation stability. Alternatively, polyimide materials have drawn more and more attentions as the pervaporation membrane material in recent years, with their superior mechanical strength and chemical stability. Here we mainly introduce our research works on the polyimide membranes for the pervaporation separations in recent years, including the molecular design of membrane materials and the structural optimization of membrane morphologies. We start with the commercial polyimide materials with suitable chemical structures and physical properties. Further chemical modifications (crosslinking, surface grafting, etc.) and morphology optimization are also employed to achieve the improved pervaporation performance and the long-term stability of the membranes. Additionally, based on the practical separation system, we also design and synthesize several new types of polyimide membranes with crosslinking and thermally-cyclodehydrated modifications. Compared to the commercial polyimide materials, the synthetic polyimides have the optimized molecular structures and superior separation efficiency.