Surface modification of microporous polypropylene membranes by plasma-induced graft polymerization of α-allyl glucoside

To change the surface property from hydrophobic to hydrophilic and to improve the antifouling property, the N-2-plasma-induced graft polymerization of sugar-containing monomer [alpha-allyl glucoside (AG) in this work] was carried out on microporous polypropylene hollow fiber membranes (PPHFMs) for the first time. The chemical and morphological changes of the membrane surface were confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, pure-water contact-angle, and protein adsorption measurements. It was found that the AG grafting degree increased slightly with the increase of AG monomer concentration for coating and adsorption on the membrane surface, and then it decreased when the AG concentration exceeded 0.25 g/mL. The static contact angle of pure water on the grafted membrane decreased significantly from 120 to 36degrees with the increase of the AG grafting degree from 0 to 3.46 wt %, which indicated that the membrane surface was distinctly changed from hydrophobic to hydrophilic. Most importantly, the contact-angle measurements also revealed that the hydrophilicity was permanent, and no hydrophobic recovery was observed. The pure-water flux of PPHFMs grafted with 2.50 wt % AG reached tremendously to 3.82 x 10(3) kg/(m(2).h). Furthermore, modification by AG grafting made the membrane surface less susceptible to the adsorption of bovine serum albumin. The modified membranes also give high flux recoveries after cleaning, indicating that the antifouling property of the membrane was improved.