Multiscale hierarchical design of tough hydrogels: from natural to biomimetic

Abstract

Many natural biological hydrogels, such as tendons, skin, cartilage, etc., are extremely tough, which is also a crucial merit for versatile applications of artificial hydrogels. Natural tough hydrogels serve as a vital source of inspiration for developing synthetic counterparts. This review begins with six representative examples of tough natural hydrogels. A thorough discussion of their unique structures and material compositions leads to the reasoning of toughness from the perspective of multiscale hierarchical design: based on the effective control of materials and structures at the molecular-nano–micro scales, as well as synergistic interactions between the different hierarchical scales. Following these design principles, we summarize the design strategies for biomimetic tough hydrogels, and the latest advanced applications of biomimetic tough hydrogels are further explored. Finally, it concludes by discussing the current challenges and prospects concerning the fabrication and application of biomimetic hydrogels.