Bio-inspired zwitterionic copolymers for antifouling surface and oil-water separation

Inspired by marine mussels, dopamine chemistry was widely used in the field of surface chemistry as an adhesion base for the synthesis of antifouling coatings. Zwitterions have antifouling properties due to their special structures and are widely used in the medical implants, drug delivery, and separation membranes. We combined the catecholic derivative dopamine methacrylamide (DMA) and the zwitterionic monomer 2-methacryloyloxyethylphosphocholine (MPC) to design copolymers with both adhesion property and antifouling property for surface modification. The synthesized P(DMA-co-MPC) copolymers could adsorbed on the substrate surfaces with DMA as anchor by a “grafting to” method. The differences in surface wettability, antifouling property and oil-water separation performance of the copolymer modified surfaces were investigated. It is demonstrated that copolymer-modified substrates have excellent antifouling performance in resistance to protein adsorption and repelling oil attachment, due to its hydrophilic surface in air and the oleophobic surface underwater. Higher MPC content in copolymer would enhance the repulsive force between polymer surface and the colloid probe in water. By using P(DMA-co-MPC)-modified stainless steel mesh and non-woven fabric as separation membranes, n-hexane/water mixture could be successfully separated with an efficiency above 97%. The P(DMA-co-MPC) copolymer modified stainless steel mesh possessed good applicability, sustainable recycling and harsh conditions resistance. Additionally, oil-water separation efficiency would be pronounced by modifying the stainless steel mesh in a basic or salty polymer solution.