Synthesis, characterization and anti-fouling properties of poly(ethylene glycol) grafted poly(vinylidene fluoride) copolymer membranes

Methoxypoly(ethylene glycol) monomethacrylate (PEGMA) graft-copolymerized poly(vinylidene fluoride) (PVDF) (the P(PEGMA)-graft-PVDF copolymer) was synthesized. The PVDF homopolymer in N-methyl-2-pyrrolidone (NMP) solution was first pretreated with ozone and the peroxide content of the ozone-treated PVDF was determined by assaying with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The activated PVDF was then subjected to graft copolymerization with the PEGMA macromonomer in NMP. The microstructures and compositions of the P(PEGMA)-graft-PVDF copolymers were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), elemental analysis, differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. Ultra-filtration (UF) membranes were prepared from the P(PEGMA)-graft-PVDF copolymer by the phase-inversion method. The bulk and the surface compositions of the membranes were determined by elemental analysis and XPS, respectively. In general, the graft concentration increases with the PEGMA macromonomer concentration. Angle-resolved XPS analyses of the UF membranes prepared from the copolymer revealed a substantial surface enrichment of the hydrophilic PEGMA component. The morphology of the membranes was studied using scanning electron microscopy (SEM). The UF membrane prepared from the P(PEGMA)-graft-PVDF copolymer with a graft concentration ([PEGMA]/[CH2CF2] ratio) above 0.06 was effective in preventing bovine serum albumin (BSA) adsorption.