Tuning membrane surfaces via polydopamine-mediated click reaction and analysis of antifouling properties

The introduction of zwitterionic polymers into porous membranes is an important technique for imparting antifouling properties. However, the lack of methods for modifying polymer layers with controlled physical characteristics on inert membrane pores has resulted in an incomplete evaluation of how polymer structure and density affect fouling properties. This study aims to address this issue by creating reactive groups through a thin layer of precoated polydopamine (PDA), followed by polymer immobilization using a density-controllable click reaction that takes polymer–solvent interactions into account. The proposed method facilitates the formation of a durable PDA layer through thermal annealing at a moderate temperature. A grafting-to approach is used for polymer immobilization, which usually leads to a low graft density; however, polymer density can be controlled in the brush region by changing the reaction solvent. This study demonstrates the high reproducibility and accuracy of this membrane modification method using various characterization techniques. Additionally, the impact of polymer density on antifouling performance is assessed through dynamic fouling tests. • Density-controllable grafting-to approach on a polydopamine (PDA) coated membrane enables precise polymer modification. • The low durability of PDA resulting from insufficient polymerization is addressed through thermal annealing of the membrane. • The impact of density of the zwitterionic polymer brush on antifouling performance is assessed through dynamic fouling tests.