Strong-adhesion and nonfouling self-generating zwitterionic Janus hydrogel paint

Zwitterionic hydrogel paints are promising and ecofriendly materials to prevent biofouling and oil contamination. However, the weak adhesion of hydrogel paints to substrates and tedious fabrication and coating processes limit their practical applications. Herein, a novel self-generating zwitterionic Janus hydrogel paint consisting of a polymer copolymerized by methyl methacrylate (MMA), tertiary carboxybetaine triisopropylsilyl ester ethyl acrylate (TCBSi), and 3-(methacryloxypropyl) trimethoxysilane (KH570) is reported. The polymer, when coated on a substrate, self-crosslinks into the polymer network and interlinks to the substrate during curing. This polymer decouples polymerization from the crosslinking and interlinking processes. When used underwater, the top layer of the coating rapidly hydrolyzes and self-generates a zwitterionic hydrogel layer, whereas the hydrophobic bottom layer remains unhydrolyzed. Adhesion tests show that this coating has considerably stronger adhesion strength than traditional zwitterionic hydrogel coatings due to the synergistic effect of hydrophobic interactions and interface bonding. Moreover, it has excellent resistance to protein, bacteria (Escherichia coli, Staphylococcus aureus, and Pseudomonas sp.), and diatom (Navicula incerta). The self-generating zwitterionic Janus hydrogel coating can also prevent oil contamination. This study serves as a promising avenue for the design and fabrication as well as practical application of self-generating zwitterionic Janus hydrogel paint with strong substrate adhesion.