Surface grafting of zwitterionic and PEGylated cross-linked polymers toward PVDF membranes with ultralow protein adsorption

It remains a major challenge to prepare membranes with minimal protein adsorption for bio-related applications. In this work, modified polyvinylidene difluoride (PVDF) membranes having ultralow protein adsorption were prepared by grafting zwitterionic and PEGylated cross-linked polymers onto the membrane surface. The PVDF membrane was first treated with alkaline and tethered with cross-linked polyethylene glycol diacrylate (CPEGDA) via ATRP. By reacting the abundant alkene group M the periphery of CPEGDA with cystine or monomethyl PEG thiol (MPEG-SH, M = 200, 600, 2000) by thio-ene reaction, the membrane surface was tethered with high density protein repellent groups. The PVDF-g-CLPEG2000 membrane shows the best performance and its bovine serum albumin (BSA) and bovine serum fibrinogen (BFG) adsorptions can be lowered to only 1/50 and 1/40 that of the original PVDF membrane, respectively. Similar fouling tendencies were observed in the dynamic filtration process. This work addresses the significance of cross-linked grafting on altering membrane surface properties.