Amphiphilic ABA-type triblock copolymers for the development of high-performance poly(vinylidene fluoride)/poly(vinyl pyrrolidone) blend ultrafiltration membranes for oil separation

ABA-type amphiphilic triblock copolymers (TBCs) were synthesized by a reversible addition fragmentation chain transfer (RAFT) process with a telechelic polystyrene macro-RAFT agent and 4-[n-(acryloyloxy)alkyloxy]benzoic acid monomers. Ultrafiltration (UF) membranes were fabricated by a phase-inversion process with blends of the TBC, poly(vinylidene fluoride) (PVDF), and poly(vinyl pyrrolidone) (PVP) in dimethylformamide. The UF-fabricated membranes were characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, thermogravimetric analysis, and differential scanning calorimetry. Pure water permeation, molecular weight cutoff values obtained by the permeation of different molecular weight polymers as probe solutes, bovine serum albumin (BSA) solution permeate flux, and oil-water emulsion filtration tests were used to evaluate the separation characteristics of the fabricated membranes. The tripolymer blend membranes exhibited a higher flux recovery ratio (FRR) after the membrane was washed with sodium lauryl sulfate (0.05 wt %) solution for a BSA solution (FRR=88%) and oil-water emulsion (FRR=95%) feeds when than the PVDF-PVP blend membrane (57 and 80% FRR values for the BSA solution and oil-water emulsion, respectively). The pendant carboxylic acid functional moieties in this ABA-type TBC have potential advantages in the fabrication of high-performance membranes. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45132.