Tough wet adhesion of hydrogel on various materials : mechanism and application

Abstract

In nature, robust interfacial adhesion plays crucial roles in maintaining integration and functionality of various physiological structures including tendon and cartilage to bones and epidermis to dermis in mammalian skins. For instance, the bonding of tendon and cartilage to bone is extremely tough (e.g., interfacial toughness ~800 Jm-2 ), yet such tough interfaces have not been achieved between synthetic hydrogels and various types engineering solids including rigid nonporous solids and elastomers. In this study, we report a strategy to design extremely robust interfacial bonding of synthetic hydrogeis containing 90 % water to various types of rigid engineering solids, precious metals and commonly-used elastomers. The design strategy is to anchor the long-chain polymer networks of tough hydrogels covalently to various solid surfaces, which can be achieved by diverse surface chemical treatments. We discuss the mechanism behind the proposed design strategy to further understand the tough wet adhesion of hydrogels in engineering and biological situations. We also demonstrate multiple novel applications of robust hydrogel-solid hybrids for both rigid engineering solids and elastomers. We discuss details of such new class of applications and their potential usefulness in diverse fields.