Thermo-responsive modification and properties study of PVDF flat membrane

A thermo-responsive membrane, PVDF-g-PNIPAAm, was successfully prepared from poly(vinylidene fluoride) (PVDF) membrane through surface-initiated atom transfer radical polymerization (ATRP) of a thermo-responsive monomer, N-isopropyl acrylamide (NIPAAm). The effect of the mass ratio of PVDF membrane to NIPAAm monomer on ATRP was studied in detail. The grafting copolymer was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that the NIPAAm was successfully grafted on the PVDF membrane, the membrane pores became smaller and the mass ratio 1:8 of PVDF membrane to NIPAAm was in favor of surface-initiated ATRP. The thermal stability of PVDF membrane and PVDF-g-PNIPAAm membranes was characterized by differential scanning calorimetry (DSC). Contact angles of membrane surface, water penetration and protein solution permeation were tested. Water contact angles of PVDF membrane reduced after the surface grafting of NIPAAm, which illuminated that the hydrophilicity of the grafted membrane was improved. The PVDF-g-PNIPAAm membranes exhibited good thermo-responsive permeability and antifouling property.