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Preparation and Characterization of pH-Sensitive Polyethersulfone Membranes Blended with Poly(methyl methacrylate-co-maleic anhydride) Copolymer

The current study aims to endow polyethersulfone (PES) hollow fiber membranes (HFMs) with improved pH-sensitivity by blending a random copolymer of poly(methyl methacrylate-co-maleic anhydride) (P(MMA-MA)). It was found that PES membrane modified by random copolymer had more obvious pH-sensitivity than those by alternative copolymer; while low molecular weight copolymer modified PES membrane had no pH-sensitivity. P(MMA-MA) was synthesized by a controlled dosing method via free radical polymerization and characterized by Fourier transform infrared spectroscopy (FTIR) analysis, nuclear magnetic resonance (1H NMR), elemental analysis, gel permeation chromatography technique (GPC), and differential scanning calorimetry (DSC) measurement. Scanning electron microscopy (SEM) was used to investigate the morphology of the HFMs. The modified HFMs showed excellent pH-sensitivity, pH-reversibility and hysteresis of water flux. Through the ultrafiltration of PEG solution, we investigated the pore size change and the electroviscous effect on the water flux of the modified HFMs. Meanwhile, the modified membranes were stable with respect to the mechanical force (pressure) and exhibited good ability of Cu2+ adsorption.