Hierarchical structures invoked by hydrogen binding domains based on hydrogen-bonded organic frameworks for ultra-tough elastomers

Abstract

Elastomers are one of the promising rubber materials, but high mechanical strength at the expense of flexibility, toughness and adhesiveness has offset their advantages. It is pivotal and challenging to balance the energy dissipation of the elastomers. Herein, the hierarchical structure of elastomers based on hydrogen-bonded organic frameworks (HOFs) hard phase and polyurethane soft phase has been reported. The hard HOFs invoke hydrogen binding domains to form multiple noncovalent interactions between HOFs and polyurethane, which facilitates the energy dissipation under external force, while soft and ductile polyurethane chains maintain the integrity of elastomers. The tensile strength and toughness of as-prepared elastomers are as high as 8.01 MPa ± 0.34 MPa and 80.52 MJ m⁻³ ± 11.46 MJ m⁻³, respectively, which greatly surpass those in the polyurethane counterpart (2.76 MPa ± 0.20 MPa and 27.48 MJ m⁻³ ± 3.84 MJ m⁻³). The ultra-high toughness and elasticity endow the elastomers with splendid and repeatable adhesiveness toward various substrates. Benefiting from the strong mechanical performance, the resultant elastomer sensors could accurately recognize the gesture during operating electronic products with recognition accuracy over 94%. This work provides a promising approach to construct high-performance elastomers for the development of flexible electronics.