Nanocomposite adhesive hydrogels: from design to application

With the rapid development of hydrogels, hydrogel adhesion has attracted increasing attention in the last decade, but strong adhesion remains a challenge due to the large amount of water in hydrogels. The factors that affect hydrogel adhesion mainly include chemistries of bonds, topologies of connection, and mechanisms of energy dissipation. Strategies such as surface modification, surface initiation, bulk modification, bridging polymers, topological adhesion, and the use of nanocomposites have been developed to achieve strong hydrogel adhesion. In nanocomposite hydrogels, nanoparticles interlink with polymer chains to form strong bonds, which lower adhesion energy and offer energy dissipation, thus enhancing the adhesion. This review emphatically outlines nanocomposite adhesive hydrogels from design to application and provides useful understanding for the design and further development of nanocomposite adhesive hydrogels.