Hydrogels are crosslinked polymer networks swollen with water. Owing to their soft and water-containing nature, hydrogels are promising materials for applications in many fields, such as biomedical engineering, soft robotics and environmental studies. One of the main obstacles to the practical application of hydrogels is their low mechanical strength and toughness. Since the 2000s, many breakthroughs in the development of mechanically strong and tough hydrogels have led to enormous advances in the study of soft materials and our understanding of their failure mechanisms. Research has also been conducted on long-term mechanical stability — that is, the cyclic fatigue resistance and self-strengthening properties of hydrogels — to enable their application as load-bearing materials. This Review provides a comprehensive overview of the design principles for tough hydrogels. Strategies to obtain self-growing and reinforced hydrogels that can adapt to their surrounding mechanical environment are also presented.

水凝胶是用水溶胀的交联聚合物网络。由于其柔软且含水的性质，水凝胶是在生物医学工程、软机器人和环境研究等许多领域应用的有前途的材料。水凝胶实际应用的主要障碍之一是其机械强度和韧性较低。自 2000 年代以来，机械强度和韧性水凝胶的开发取得了许多突破，导致软材料研究和我们对其失效机制的理解取得了巨大进步。还对长期机械稳定性（即水凝胶的循环疲劳性能和自增强性能）进行了研究，以使其能够作为承载材料应用。本综述全面概述了坚韧水凝胶的设计原理。还提出了获得能够适应周围机械环境的自生长和增强水凝胶的策略。