Improving the hydrophilicity of poly(vinylidene fluoride) porous membranes by electron beam initiated surface grafting of AA/SSS binary monomers

Poly(vinylidene fluoride) (PVDF) membranes were pre-irradiated by electron beam in vacuum, and then the hydrophilic sulfonate groups were introduced by the single step grafting method with binary monomer solution of acrylic acid (AA) and sodium 4-styrenesulfonate (SSS). The effect of binary monomer ratio and pH of reaction solution on the degree of grafting was investigated. The surface chemical change was characterized by Fourier transform infrared attenuated total reflection spectroscopy (FT-IR-ATR) and X-ray photoelectron spectroscopy (XPS). Morphological changes on the membrane surface were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface hydrophilicity of the modified membrane was characterized through water contact angle measurement. It was found that the water contact angle of the membrane surface decreased significantly when compared with the original one, indicating the improvement of the surface hydrophilicity.