Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

Oil-contaminated wastewater threatens our environment and health thus novel membrane materials with low or nonfouling properties are an immediate need for oily wastewater treatment in a cost-effective and environmentally friendly manner. In this study, three types of amphiphilic random, gradient, and block copolymers with similar molecular weights and chemical compositions, based on poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate (TFOA), were synthesized by the reversible addition-fragmentation chain transfer (RAFT) method. The amphiphilic Poly(ether sulfone) membranes were then fabricated by blending with these copolymers via a facile coupled process of nonsolvent induced phase separation and surface segregation. Accompanying the phase inversion process of polymer matrix, the hydrophilic and hydrophobic segments in the amphiphilic modifiers would migrate and immobilize onto the membrane surfaces. This surface segregation process leaded to a chemical heterogeneous membrane surface comprising both hydrophilic PEGMA and low surface energy PTFOA brushes, which was confirmed by X-ray photoelectron spectroscopy (XPS) and surface wettability analyses. Oil-in-water emulsion filtration test of the membranes displayed a lower permeate flux decline and a higher flux recovery (as high as 99.8%), establishing their considerably elevated antifouling properties. Additionally, cyclic oil/water separation and long-term underwater immersion tests demonstrated that the as-prepared membranes modified by these amphiphilic additives possessed excellent antifouling stabilities. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 739-750, 2017