Hydrogel Adhesion: A Supramolecular Synergy of Chemistry, Topology, and Mechanics

TLDR

Hydrogel adhesion to diverse substrates is essential for many applications, and recent advances have revealed it as a supramolecular phenomenon that bridges multiple disciplines. The review outlines immediate opportunities for fundamental research and practical applications in hydrogel adhesion. Hydrogel adhesion involves connections via covalent or noncovalent bonds, polymer chains, networks, or nanoparticles, and energy dissipation during separation occurs through bond cleavage, chain retraction, and bulk hysteresis across multiple length scales. Strong hydrogel adhesion arises from the synergy of bond chemistry, connection topology, and dissipation mechanics, enabling permanent, reversible, degradable, or on‑demand detachable adhesion across a wide range of materials and operations.

Abstract

Abstract Adhering hydrogels to various materials is fundamental to a large array of established and emerging applications. The last few years have seen transformative advances in achieving strong hydrogel adhesion, which is a supramolecular phenomenon. Two adherends connect through covalent bonds, noncovalent complexes, polymer chains, polymer networks, or nanoparticles. Separating the adherends dissipates energy through cascading events across length scales, including bond cleavage, chain retraction, and bulk hysteresis. A unifying principle has emerged: strong hydrogel adhesion requires the synergy of chemistry of bonds, topology of connection, and mechanics of dissipation. This synergy characterizes hydrogel adhesion to various materials (another hydrogel, tissue, elastomer, plastic, metal, glass, and ceramic) in various operations (cast, coat, print, attach, pierce, and glue). Strong adhesion can be made permanent, reversible, degradable, or on‐demand detachable. The development of hydrogel adhesion and its applications adheres disciplines, discovers interlinks, and forges cohesion. Discussed throughout the review are immediate opportunities for fundamental studies and practical applications.