Improved protein-adsorption resistance of polyethersulfone membranes via surface segregation of ultrahigh molecular weight poly(styrene-alt-maleic anhydride)

A styrene-maleic anhydride (SMA) alternating copolymer with ultrahigh molecular weight (Mw > 106) synthesized in super critical carbon dioxide (SC CO2) medium was used as hydrophilic polymeric additive in the preparation of polyethersulfone (PES) membranes. The PES/SMA blend membranes were prepared by immersion precipitation process. X-ray photoelectronic spectroscopy (XPS) measurements confirmed that the hydrolyzed SMA preferentially segregated to membrane–coagulant interface during membrane formation. For the PES/SMA blend membranes, no big change was observed in the cross-sectional structure and the mechanical properties were well maintained after SMA addition except that a thicker top layer was formed. The surface morphology analysis by atomic force microscopy (AFM) showed that the membrane surface roughness increased with the added SMA amount. The results of water contact angle, water absorbance measurements and static protein adsorption experiments revealed that the surface enrichment of SMA endowed PES/SMA blend membranes with significantly improved surface hydrophilicity and protein-adsorption resistance.