Preparation and characterization of modified PVDF membrane induced by argon plasma with enhanced antifouling property

Poly(vinylidene fluoride) (PVDF) flat sheet membranes were fabricated by phase inversion method and modified with poly(acrylic acid) grafting induced by argon plasma. The effects of solvent type and coagulation bath temperature on membrane morphology and water flux were investigated. PVDF dopes were prepared by dissolving polymer powder in three different solvents: N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF) and 1-methyl-2-pyrrolidone (NMP). The differences in solubility parameters between the non-solvent, solvent and PVDF affected the phase inversion process, and the resulting morphology was observed by scanning electron microscopy (SEM). The results revealed that membranes fabricated using DMF and DMAc as solvents both exhibited short finger-like structures with spongy substrates. Also, the membrane morphology was altered toward a finger-like structure when the temperature of the coagulation bath was increased from 5 degrees C to 55 degrees C. The membranes with the highest water flux were modified with different concentrations of acrylic acid monomer and characterized by attenuated total reflection (ATR), SEM, atomic force microscopy (AFM), contact angle measurement and filtration tests. Results indicated that the membranes modified with higher concentrations of acrylic acid monomer displayed higher hydrophilicity and improved antifouling properties.