Stretchable hydrogels with low hysteresis and anti-fatigue fracture based on polyprotein cross-linkers

• Published in: Nature communications 2020-08, Vol.11 (1), p.4032-4032, Article 4032
• Main Authors: Lei, Hai, Dong, Liang, Li, Ying, Zhang, Junsheng, Chen, Huiyan, Wu, Junhua, Zhang, Yu, Fan, Qiyang, Xue, Bin, Qin, Meng, Chen, Bin, Cao, Yi, Wang, Wei
• Format: Article
• Language: English
• Subjects: 119/118; 147/3; 639/301/1023/303; 639/301/923/1028; 639/638/298/923/1028; 82/29; 82/80; 82/83; 96/34; Acrylic Resins - chemistry; Biosensors; Crack propagation; Cross-Linking Reagents - chemistry; Crosslinking; Design; Fatigue; Fatigue failure; Flexible components; Fluorescence; Fracture toughness; Humanities and Social Sciences; Hydrogels; Hydrogels - chemistry; Hysteresis; Interfaces; Man-machine interfaces; Mechanical analysis; Mechanical Phenomena; multidisciplinary; Percolation; Polymers; Polyproteins - chemistry; Proteins; Science; Science (multidisciplinary); Strain; Stress, Mechanical; Stretchability
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-17877-z

Hydrogel-based devices are widely used as flexible electronics, biosensors, soft robots, and intelligent human-machine interfaces. In these applications, high stretchability, low hysteresis, and anti-fatigue fracture are essential but can be rarely met in the same hydrogels simultaneously. Here, we demonstrate a hydrogel design using tandem-repeat proteins as the cross-linkers and random coiled polymers as the percolating network. Such a design allows the polyprotein cross-linkers only to experience considerable forces at the fracture zone and unfold to prevent crack propagation. Thus, we are able to decouple the hysteresis-toughness correlation and create hydrogels of high stretchability (~1100%), low hysteresis (< 5%), and high fracture toughness (~900 J m −2 ). Moreover, the hydrogels show a high fatigue threshold of ~126 J m −2 and can undergo 5000 load-unload cycles up to 500% strain without noticeable mechanical changes. Our study provides a general route to decouple network elasticity and local mechanical response in synthetic hydrogels. High stretchability, low hysteresis and anti-fatigue fracture are essential for hydrogel-based devices but it is rare to achieve. Here the authors demonstrate a hydrogel design using tandem-repeat proteins as the cross-linkers and random coiled polymers as the percolating network which results in high stretchability, low hysteresis and high fracture toughness.