Simultaneously Toughening and Stiffening Elastomers with Octuple Hydrogen Bonding
Yizhi Zhuo, Zhijie Xia, Yuan Qi, Takashi Sumigawa, Jianyang Wu, Petr Šesták, Yinan Lu, Verner Håkonsen, Tong Li, Feng Wang, Wei Chen, Senbo Xiao, Rong Long, Takayuki Kitamura, Liangbin Li, Jianying He, Zhiliang Zhang
Abstract
Abstract Current synthetic elastomers suffer from the well‐known trade‐off between toughness and stiffness. By a combination of multiscale experiments and atomistic simulations, a transparent unfilled elastomer with simultaneously enhanced toughness and stiffness is demonstrated. The designed elastomer comprises homogeneous networks with ultrastrong, reversible, and sacrificial octuple hydrogen bonding (HB), which evenly distribute the stress to each polymer chain during loading, thus enhancing stretchability and delaying fracture. Strong HBs and corresponding nanodomains enhance the stiffness by restricting the network mobility, and at the same time improve the toughness by dissipating energy during the transformation between different configurations. In addition, the stiffness mismatch between the hard HB domain and the soft poly(dimethylsiloxane)‐rich phase promotes crack deflection and branching, which can further dissipate energy and alleviate local stress. These cooperative mechanisms endow the elastomer with both high fracture toughness (17016 J m −2 ) and high Young's modulus (14.7 MPa), circumventing the trade‐off between toughness and stiffness. This work is expected to impact many fields of engineering requiring elastomers with unprecedented mechanical performance.