Underwater adhesives receive extensive attention due to their wide applications in marine explorations and various related industries. However, current adhesives still suffer from excessive water absorption and lack of spontaneity. Herein, we report an autonomous underwater adhesive based on poly(2-hydroxyethyl methacrylate-co-benzyl methacrylate) amphiphilic polymeric matrix swollen by hydrophobic imidazolium ionic liquid. The as-prepared adhesive is tough and flexible, showing little to none instantaneous underwater adhesion onto the PET substrate, whereas its adhesion energy on the substrate can grow more than 5 times to 458 J·m⁻² after 24 hours. More importantly, this process is entirely spontaneous, without any external pressing force. Our comprehensive studies based on experimental characterizations and molecular dynamic simulations confirm that such autonomous adhesion process is driven by water-induced rearrangement of the functional groups. It is believed that such material can provide insights into the development of next-generation smart adhesives.

We review the present state and advances of the design and preparation strategies for fabricating multidimensional sensors based on anisotropic conducting networks.