Fabrication of surface microstructure for the ultrafiltration membrane based on “active–passive” synergistic antifouling and its antifouling mechanism of protein

In this work, four types of ultrafiltration membranes with different antifouling capacities were prepared by the introduction of maleic anhydride (MA), polyethylene glycol (PEG), polyethyleneimine (PEI), and PEG-g-PEI via “surface deposition–grafting” technique. The microstructure of the membrane surface was characterized and antifouling capacity was determined by investigating the influence of functional hydrophilic groups on the antifouling capacity and the formation process of the fouling layer. It was found that the membrane grafted with PEG-g-PEI had better anti-protein-fouling capacity than that of other membranes. The flux recovery rate stayed at 98.26% despite the higher positive charge of its surface. The irreversible resistance was as low as 0.54% and could effectively delay the formation of irreversible fouling. Also, the adhesion of bovine serum albumin (BSA) on the membrane surface was reduced to only 28.59 nN. The “active–passive” synergistic mechanism of antifouling increased the dispersion and flocculation capacities of the grafted functional polymer chains. The repulsion effect of the hydration layer was also enhanced. The effectiveness of this proposed mechanism was demonstrated based on research on the antifouling ability, the characterization of the hydration layer microstructure, and the adhesion of BSA on the membrane surface. This work provides a reference for fabricating a membrane with advanced antifouling capacity and has a deeper understanding on the antifouling mechanism.