A novel controlled grafting chemistry fully regulated by light for membrane surface hydrophilization and functionalization

A novel controlled grafting chemistry was put forward for membrane surface hydrophilization and functionalization. The chemistry can be fully regulated by light and combines UV-irradiated reaction attaching the initiators for atom transfer radical polymerization (ATRP) with the following visible-light-driven ATRP initiated from a microporous polypropylene membrane (MPPM) surface. A series of hydrophilic and polar methacrylate polymers, including methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), and polyethylene glycol methacrylate (OEGMA), were grafted onto the membrane surface by using Ir-based photoredox catalyst and irradiating with fluorescence lamps. The modified membranes were characterized by FTIR, XPS and FESEM. The results indicated that grafted polymer can significantly alter membrane chemistry and morphology. The evolution of the grafting yield with polymerization time reveals that the polymer growth from the membrane surface is consistent with a controlled process. High grafting yields of 500-1400 µg/cm2 can be obtained by optimizing irradiation time, monomer concentration and catalyst concentration conditions. The dormant chain ends of grafted polymer can be reactivated to produce corresponding diblock copolymer brushes. The grafting of PHEMA and POEGMA can double the pure water flux and greatly depress protein adsorptions.