Controllable modification of polymer membranes by LDDLT plasma flow: Grafting acidic ILs into PPF membrane for catalytic performance

This article focused on the membranes covalent bearing ionic liquid for catalytic performance. The polypropylene fibrous (PPF) membranes was activated by long-distance and dynamic low-temperature plasma flow. Thereafter, it was successfully grafted with 1-vinylimidazole acidic ionic liquids (ILs) through free radical polymerization. The membranes formed were characterized through Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, bubble pressure method filter membrane pore size analyzer, electronic universal testing machine and contact angle meter. Catalytic hydrolysis of inulin polysaccharide into fermentable reducing sugars using the ILs grafted PPF (ILs-g-PPF) membranes was also evaluated by the DNS method. The results confirmed the successful and steady grafting onto the surfaces and the pore walls of PPF membranes. The resulting ILs-g-PPF membrane exhibited high catalytic activity for hydrolysis of inulin and could be easily separated from the reaction mixture. After two rinses and six times of hydrolysis for the same feed, the hydrolysis ratio was close to 100%. Moreover, the spent ILs-g-PPF membrane was of good reusability and stability. Catalytic PPF membranes obtained by the ILs immobilization have advantages over the ILs themselves for chemical industrial application.