Vapor induced phase separation towards anion-/near-infrared-responsive pore channels for switchable anti-fouling membranes

Abstract

As an important type of smart membrane, stimuli-responsive membranes with switchable separation capability and permeability are urgently needed for developing advanced filtration membranes. In this study, smart membranes with anion-/near-infrared (NIR)-responsive and improved anti-fouling properties were fabricated by introducing poly(ionic liquid) (PIL) modified Fe₃O₄ nanoparticles on the surfaces and pore channels of polyethersulfone membranes through the vapor induced phase separation (VIPS) method. Thanks to the anion-/NIR-responsiveness of the nanoparticles, adjustable surface wettability and pore sizes of the membranes were obtained. The fluxes of the membranes were well-controlled along with adjusting the sizes of the nanoparticles via anion-exchange and NIR irradiation. The switchable pore size was further demonstrated by the filtration of polyethylene glycol (PEG)-800 and PEG-2000. In addition, the wettability and zeta-potential of the membrane surfaces could be adjusted by exchanging the counteranions of the immobilized PIL nanoparticles, which endowed the membranes with robust anti-fouling abilities toward biological contaminants like bovine serum albumin when changing the counteranions from hydrophilic to hydrophobic. After the counteranion exchange desorption, the intelligent membranes were then self-cleaned.