The high-performance hydrogels used for tissue repair should simultaneously provide mechanical reinforcement and interfacial adhesion. However, traditional reinforcement strategies usually rely on hydrogen bonds within the network. The inherent bonding energy and limited configurational freedom of hydrogen bonds essentially limit the chain mobility at the interface, ultimately weakening the wet adhesion. To overcome the strength-adhesion trade-off brought about by the hydrogen bond distribution, this study proposes an entropy-driven strategy that decouples the spatial distribution of hydrogen bonds and simultaneously achieves high volumetric strength and robust wet adhesion. Starting from a disordered and highly entropic mixture, hydrogen bonds then concentrate throughout the network through entropy-favorable reconfiguration, to enhance the network. The energy and conformational mismatch at the interface trigger local phase separation, reducing the interface entropy and forming a hydrogen bond-depleted nanoscale constrained water layer. This layer allows for the dynamic polymer-tissue hydrogen bond binding, achieving robust wet adhesion without loss of volumetric strength. The resulting hydrogels can quickly adhere to the tissue surface, forming a high modulus structure (approximately 13 megapascals), capable of withstanding up to 368 mmHg of static water pressure. It achieves sealing beyond physiological limits and maintains stable adhesion, demonstrating effective repair in skin injuries, oral mucosal ulcers, and heart bleeding models. This research was published in Advanced Materials under the title "Tough Hydrogels with Robust Wet Adhesion via Entropy-Driven Hydrogen Bond Reorganization".
References:
DOI: 10.1002/adma.73182