Surface modification of PVDF membrane via graft polymerization of acetic and acrylic acid

Abstract

Abstract Surface modification of polyvinylidene fluoride (PVDF) hollow fibre membranes through simple chemical treatment is carried out to graft the surface with the presence of carboxylic acid groups. This is to provide means for TiO2 immobilisation in subsequent stages for photocatalysis application. The focus of this study was to identify the highest degree of grafting in order to provide abundant potential sites for subsequent TiO2 assembly. Both acetic and acrylic acid, at varying concentrations, were used and compared as the grafting monomer. It was observed that acrylic acid provides significantly higher grafting degree compared to acetic acid. The highest degree 238 μg/cm2 was obtained at 70% acrylic acid in water, where the surface contact angle significantly reduced to 37o. The highest grafting degree obtained using acetic acid was at 60% in water, which only achieved 31 μg/cm2. Minor improvement was also observed when the solvent for grafting solution was changed from water to toluene; the grafting degree slightly improved by 2% from 238 μg/cm2 to 243 μg/cm2. Higher grafting degree shall allow for more of TiO2 to be immobilized onto the membrane in subsequent work, hence potentially leading to better photocatalysis performance.