Grafting perfluoroalkyl groups onto polyacrylonitrile membrane surface for improved fouling release property

Abstract

Abstract In this study, a novel kind of fluorinated polyacrylonitrile (PAN) membrane is prepared by grafting perfluoroalkyl groups onto aminated PAN membrane surface through the acylation reaction. The surface composition of the fluorinated PAN membranes is confirmed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The changes of membrane surface hydrophilicity, chemical heterogeneity and surface free energy after fluorination treatment are evaluated by contact angle measurement. When utilized for the ultrafiltration separation of oil/water emulsion, protein aqueous solution and polysaccharide aqueous solution, the fluorinated PAN membranes exhibit superior fouling release properties, that is, high flux recovery ratio (∼99%) and low total flux decline ratio (the minimal value is ∼13%). These results demonstrate the feasibility of grafting perfluoroalkyl groups onto the membrane surfaces to manipulate the physicochemical features and improve antifouling property. Moreover, the fluorinated PAN membranes acquire distinct reversible multi-responsive properties under ionic strength and pH stimuli.