Fabrication of alkali-resistant PVDF membranes via atom transfer radical polymerization

The increased alkali resistance of PVDF membranes helps to extend membrane life and expand membrane applications in alkaline environments. In this paper, the amphiphilic copolymer hexafluorobutyl methacrylate (HFBMA) was grafted onto PVDF membranes via atom transfer radical polymerization (ATRP), and the corrosion resistance of PVDF-g-HFBMA in alkaline solutions was investigated. PVDF-g-HFBMA was prepared by one-step method, and the grafting rate was 29 %. PVDF membrane and PVDF-g-HFBMA membrane (PVDF-H) were prepared by NIPS. 19 F NMR and gel permeation liquid chromatography (GPC) results showed that HFBMA monomer was successfully grafted onto the main chain of PVDF by ATRP. The chemical compositions of PVDF membrane and PVDF-g-HFBMA membrane before and after alkali treatment were investigated by Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS). The membrane morphology was investigated by scanning electron microscopy (SEM). HFBMA replaced fluorine atoms and grafted onto PVDF, reducing the removal of HF groups and the formation of C C on the membrane surface. Following the alkali treatment, the whiteness of the PVDF membrane decreased by 95.62 %, and the elongation at break reduced by 56.66 %. The whiteness of the PVDF-g-HFBMA membrane decreased by 42.08 %, while the elongation only reduced by 2.88 %.