Bioinspired 2D Isotropically Fatigue‐Resistant Hydrogels
Xiangyu Liang, Guangda Chen, Shaoting Lin, Jiajun Zhang, Liu Wang, Pei Zhang, Yang Lan, Ji Liu
Abstract
Abstract Engineering conventional hydrogels with muscle‐like anisotropic structures can efficiently increase the fatigue threshold over 1000 J m −2 along the alignment direction; however, the fatigue threshold perpendicular to the alignment is still as low as ≈100–300 J m −2 , making them nonsuitable for those scenarios where isotropic properties are desired. Here, inspired by the distinct structure–properties relationship of heart valves, a simple yet general strategy to engineer conventional hydrogels with unprecedented yet isotropic fatigue resistance, with a record‐high fatigue threshold over 1,500 J m −2 along two arbitrary in‐plane directions is reported. The two‐step process involves the formation of preferentially aligned lamellar micro/nanostructures through a bidirectional freeze‐casting process, followed by compression annealing, synergistically contributing to extraordinary resistance to fatigue crack propagation. The study provides a viable means of fabricating soft materials with isotropically extreme properties, thereby unlocking paths to apply these advanced soft materials toward applications including soft robotics, flexible electronics, e‐skins, and tissue patches.