Multifunctional porous materials with simultaneous high water flux, antifouling and antibacterial performances from ionic liquid grafted polyethersulfone

Abstract

Polyethersulfone (PES) porous membranes have been widely applied in water treatment due to their high chemical stability and good mechanical properties, but they still suffer from several limitations such as low water flux, serious membrane fouling, and bacterial growth. In this work, a novel PES porous membrane material was designed and prepared by chemical bonding a hydrophilic ionic liquid, 1-vinyl-3-butylimidazolium tetrafluoroborate (VBIm BF4, IL (BF4) for short) on the PES main chains via radiation induced grafting method. It was found that the IL (BF4) is miscible with PES matrix due to the specific interactions between imidazolium ring of IL (BF4) and benzene ring of PES. The radiation on the homogenous PES/IL (BF4) blends induces the in-situ grafting of IL (BF4) onto the PES main chains uniformly. The formation of IL (BF4) grafted PES (PES-g-IL (BF4)) was confirmed by NMR spectra and the grafting site was determined to be located at the C atom on benzene ring adjacent to ether oxygen atom on the main chain. The porous membranes can be easily fabricated from the synthesized PES-g-IL (BF4) by the simple immersion precipitation phase inversion strategy. The PES-g-IL (BF4) porous membranes exhibited drastically enhanced water flux, improved antifouling property and excellent antibacterial property as compared with the porous membranes from the neat PES. This work may not only enlarge the applications of PES porous membranes but also offer a new strategy to design multifunctional porous materials.