Surface grafting control of PEGylated poly(vinylidene fluoride) antifouling membrane via surface-initiated radical graft copolymerization

This work describes the surface grafting control of poly(vinylidene fluoride) (PVDF) membrane with poly(ethylene glycol) methacrylate (PEGMA) via three different modification approaches of surface-initiated radical graft copolymerization, including thermal-induced radical polymerization, surface-initiated atom transfer radical polymerization (ATRP), and low pressure plasma-induced graft-polymerization. Two different surface grafting structures of PEGylated layer, brush-like PEGMA and network-like PEGMA, on PVDF membrane surface were achieved in this study. The chemical composition and microstructure of the various surface-modified PEGylated PVDF membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), contact angle, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) measurements. Antifouling property of the modified PVDF membranes was evaluated according to the amount of protein adsorption and the filtration test for BSA solution in this study. Results show that the amount of adsorbed proteins on the modified PVDF membranes not only depends on the surface hydrophilicity and hydration capacity but also associates with the surface grafting structures of PEGylated layers on PVDF membrane surface. This study not only introduces different practical modification approaches to achieve a hydrophobic PVDF membrane grafting hydrophilic PEGMA, but also provides a fundamental understanding of various PEGylated grafting structures governing the performance of antifouling properties.