Superstretchable, yet stiff, fatigue-resistant ligament-like elastomers

• Published in: Nature communications Vol. 13; no. 1; pp. 2279 - 8
• Main Authors: Li, Mengxue, Chen, Lili, Li, Yiran, Dai, Xiaobin, Jin, Zhekai, Zhang, Yucheng, Feng, Wenwen, Yan, Li-Tang, Cao, Yi, Wang, Chao
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.04.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 140/133; 639/301/1023/303; 639/301/923/1028; 639/638/455/303; Chemical Phenomena; Crosslinking; Design; Elastic Modulus; Elastomers; Energy dissipation; Fatigue strength; Humanities and Social Sciences; Ligaments; Lithium; Lithium ions; Mechanical properties; Modulus of elasticity; multidisciplinary; Polymers; Polymethyl methacrylate; Polymethylmethacrylate; Robotics; Science; Science (multidisciplinary); Stiffness; Stretchability; Toughness
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-30021-3

Ligaments are flexible and stiff tissues around joints to support body movements, showing superior toughness and fatigue-resistance. Such a combination of mechanical properties is rarely seen in synthetic elastomers because stretchability, stiffness, toughness, and fatigue resistance are seemingly incompatible in materials design. Here we resolve this long-standing mismatch through a hierarchical crosslinking design. The obtained elastomer can endure 30,000% stretch and exhibit a Young’s modulus of 18 MPa and toughness of 228 MJ m −3 , outperforming all the reported synthetic elastomers. Furthermore, the fatigue threshold is as high as 2,682 J m −2 , the same order of magnitude as the ligaments (~1,000 J m −2 ). We reveal that the dynamic double-crosslinking network composed of Li + -O interactions and PMMA nanoaggregates allows for a hierarchical energy dissipation, enabling the elastomers as artificial ligaments in soft robotics. Stiffness, toughness, and fatigue resistance are seemingly incompatible in materials design. Here the authors demonstrate a hierarchical crosslinking strategy using lithium ion oxygen interactions and PMMA nanoaggregates to enable energy dissipation in the network, leading to stiff yet tough polymer materials.