A mussel-inspired catecholic ABA triblock copolymer exhibits better antifouling properties compared to a diblock copolymer

Antifouling material design is vital for many fields and there are several factors that influence the antifouling performance such as the surface chemical composition, roughness, conformation and so on. We expect that any polymer topological effect observed in bulk or in solution will be amplified by adding an additional boundary such as a grafting surface. The choice of polymers and the type of grafting technique employed for surface modification are important aspects. Inspired by the adhesive nature of mussels and the antifouling properties of zwitterions, amphiphilic ABA triblock and AB diblock copolymers with A as a catechol-anchor and B as a hydrophilic zwitterionic block were designed and fabricated to have the same composition but different chain lengths. Compared with its diblock analogue, the triblock copolymer aggregated to form flower-like micelles in aqueous solution and resulted in a smoother and denser coating on the surface, which afforded better antifouling properties. This was primarily attributed to the different polymer conformations on the surface due to the similar chemical compositions and surface roughness. The force-vs.-separation curves revealed that triblock copolymers provided an enhanced steric stabilization of the surface due to the loop conformation, which is probably the reason for the triblock copolymer having an improved resistance towards biofoulants. The chain architectures of block copolymers can influence their self-assembly characteristics both in aqueous solution and on a solid surface, thus, determining the surface properties. The results clearly demonstrate that anchored triblock copolymers with a loop conformation are prominent for protein-resistance.