Preparation of poly(vinylidene fluoride) microfiltration membrane with uniform surface-copolymerized poly(ethylene glycol) methacrylate and improvement of blood compatibility

This work describes the surface modification and characterization of poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes grafted with poly(ethylene glycol) methacrylate (PEGMA) via surface-activated ozone treatment and thermally induced graft copolymerization. The chemical composition and microstructure of the surface-modified PVDF membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), contact angle, and atomic force microscopy (AFM) measurements. Blood compatibility of the modified membranes was evaluated by the biofouling property of the platelet adhesion observed by scanning electron microscopy (SEM) and the plasma protein adsorption determined by an enzyme-linked immunosorbent assay (ELISA). In general, the grafting density of the copolymerized PEGMA and the hydrophilicity on the surface of PVDF MF membranes increase with increasing macromonomer concentration of PEGMA in the reaction solution. The grafting distribution of PEGMA on the resulting membranes was found to form a uniform polymer hydrogel-like layer controlled by sufficient high content of PEGMA in the reaction solution, while their surface roughness was kept lower than that of the virgin membrane. For the platelet adhesion test, a remarkable suppression of the platelets adhered to the PVDF MF membranes grafted with PEGMA polymer was observed. In the water flux experiments, the PEGMA-grafted hydrophilic PVDF MF membranes exhibited good anti-fouling properties to substantially reduce the irreversible membrane fouling caused by platelet adhering and plasma protein adsorption as compared with the virgin hydrophobic PVDF MF membranes.