Enhanced PVDF membrane performance via surface modification by functional polymer poly(N-isopropylacrylamide) to control protein adsorption and bacterial adhesion

The aim of this work is to prepare antifouling membrane with low-biofouling property by grafted functional polymer. Surface modification of poly(vinylidene fluoride) (PVDF) membrane was carried out via a modified and simple process by grafted poly(N-isopropylacrylamide) (PNIPAAm). The grafting density of PNIPAAm was significantly improved, up to 0.90 ± 0.38 mg/cm2, thereby improving the properties and performance of the membrane. The chemical composition, thermal stability and surface morphology of pristine and modified membranes had been characterized by attenuated total reflectance fourier-transform infrared spectroscopy (ATR-FTIR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscope (AFM), respectively. After modification, the hydrophilicity of PVDF membrane was dramatically enhanced due to incorporation of PNIPAAm chains. The results of protein adsorption, microfiltration experiments and bacterial adhesion test demonstrated that the modified membrane exhibited obvious thermo-sensitive property and good antifouling capability. The maximum of flux recovery ratio (FRR), 91.59%, was obtained for the modified membrane. It is evidently believed that protein foulants was removed easily from the modified membrane surface after water washing. In addition, bacterial adhesion test revealed that the attachment of Escherichia coli on the modified membrane was reduced by 75% compared to the original membrane.