Surface segregation of segmented amphiphilic copolymer of poly (dimethylsiloxane) and poly(ethylene glycol) on poly(vinylidene fluoride) blend membrane for oil-water emulsion separation

Copolymers are used as additive for membrane preparation. Hydrolytic stability of a copolymer is enormous important for use in membrane preparation. Most of the polymers or macromonomers (methacrylate-terminated oligomers) contain vulnerable ester linkage. Herein, a relatively hydrolytically stable segmented amphiphilic copolymer (PDMS-PEG, containing urethane linkage) of poly(dimethylsiloxane) and poly(ethylene glycol) was used for the preparation blend membranes. Membranes were prepared from a blend of copolymer, poly(vinylidene fluoride) (PVDF) and poly(vinyl pyrrolidone) (PVP) by the non-solvent induced phase separation process. The copolymer is miscible with the membrane forming polymer and PVP and influences the properties of the membranes in terms of water wetting, compaction factor, and surface morphology. A membrane [PVDF-PVP-copolymer(1.7)] prepared by the addition of 1.7% w/w of copolymer in casting solution showed permeate water flux of about 280 Lm(-2) h(-1), and oil rejection of > 99%, with flux recovery ratio as high as > 99% after filtration of surfactant free and surfactant stabilized oil-in-water emulsions at applied pressure of 0.35 bar. The good antifouling property of the membrane is attributed to the hydration effect of PEG segments and fouling release property of PDMS segments.