Preparation of functional poly(ether–urethane) for immobilization of human living cells 1. Surface graft polymerization of poly(ether–urethane) with 2-(dimethylamino)ethyl methacrylate and quaternization of grafted membrane

Functional Poly(ether–urethane) (PEU) was prepared by grafting 2-(dimethylamino)ethylmethacrylate(DMAEM) onto the membrane surface and quaternizing the grafted membrane. Graft polymerization was conducted by combining photo-oxidation and irradiation grafting. PEU membrane was photo-oxidized firstly in hydrogen peroxide solution and then grafted with DMAEM under UV light. The grafted membrane was quaternized with iodomethane. The results showed that the hydroperoxide groups content was dependent on photo-oxidization time and reached a maximum at about 8 h; degree of grafting increased with hydroperoxide groups content, irradiation time and monomer concentration. Irradiation under UV light enhanced the graft polymerization. The grafted DMAEM could be quaternized completely. ATR–FTIR spectra, X-ray photoelectron spectroscopy, optical microscopic photographs and water absorption percent characterized the grafted and quaternized copolymers. ATR–FTIR and XPS analysis further verified the occurrence of graft polymerization and quaternization reaction. The photographs of the grafted and quaternized membranes with a low degree of grafting consisted of regular cobblestones on the surfaces while the grafted membranes with a very high degree of grafting showed minimal morphology, and the cobblestones recurred after being quaternized. Water absorption percent increased slightly with the degree of grafting and rapidly when the grafted membrane was quaternized.