pH-responsive and fouling-release properties of PES ultrafiltration membranes modified by multi-functional block-like copolymers

A novel kind of block-like copolymer poly(butyl methacrylate)-b-poly(methacrylic acid)-b-poly(hexafluorobutyl methacrylate) (PBMA-b-PMAA-b-PHFBM) with hydrophobic segments, hydrophilic segments and fluorine-containing segments was prepared by free radical polymerization method. The copolymers were incorporated into PES ultrafiltration membranes through a wet phase inversion method. The surface enrichment of hydrophilic segments and fluorine-containing segments of the copolymer due to the spontaneous and forced surface segregation during non-solvent induced phase separation process was confirmed by X-ray photoelectron spectroscopy (XPS). The modified membranes displayed distinct pH-responsive permeability. The water flux of PES/PBMA5-b-PMAA4.6-b-PHFBM1.1 membrane could significantly decrease from 150 L/(m2 h) to 75 L/(m2 h) in the pH region of 4.8–6.2. Meanwhile, the modified membranes exhibited desirable fouling release property mainly derived from fluorine-containing segments. The highest cleaning efficiency of the modified membranes could reach 57.4% compared with that less than 5% of the blank membranes.