Hydrophilic modification of a PSU membrane with block copolymer of PS-b-SBMA

Sulfobetaine methacrylate (SBMA) is a well-known zwitterionic molecule that can improve the hydrophilic property of hydrophobic membranes such as polysulfone (PSU). However, SBMA is too hydrophilic to dissolve in organic solvents. Hence, it is difficult to modify the polymer membranes via blending with their casting solution. This paper aims to synthesize an amphiphilic block polymers of polystyrene-block-sulfobetaine methacrylate (PS-b-SBMA) which can be well dissolved in organic solvents for membrane casting. The two PS-b-SBMA copolymers with SBMA content >28% were applied as the additives to cast the PSU ultrafiltration membrane. The PS-b-SBMA copolymer modified membranes showed lower contact angles and 3-folds higher water flux recovery after BSA treatment than the parent PSU membrane. Moreover, SEM images showed that the BSA contaminant on the modified membrane surfaces was much less than that on PSU membrane. Thus, such modified membranes can be applied to prevent protein fouling in the process of ultrafiltration.