Improving hydrophilicity and protein antifouling of electrospun poly(vinylidenefluoride-hexafluoropropylene) nanofiber membranes

 Poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) nanofiber membranes with improved hydrophilicity and protein fouling resistance via surface graft copolymerization of hydrophilic monomers were prepared. The surface modification involves atmospheric pressure glow discharge plasma (APGDP) pretreatment followed by graft copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA). The success of the graft modification with PEGMA on the PVDF-HFP fibrous membrane is ascertained by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared measurements (ATR-FTIR). The hydrophilic property of the nanofiber membranes is assessed by water contact angle measurements. The results show that the PEGMA grafted PVDF-HFP nanofiber membrane has a water contact angle of 0^o compared with the pristine value of 132^o. The protein adsorption was effectively reduced after PEGMA grafting on the PVDF-HFP nanofiber membrane surface. The PEGMA polymer grafting density on the PVDF-HFP membrane surface is measured by the gravimetric method, and the filtration performance is characterized by the measurement of water flux. The results indicate that the water flux of the grafted PVDF-HFP fibrous membrane increases significantly with the increase of the PEGMA grafting density.