Room-Temperature Healable and Mechanically Robust Polyurea-Urethane Based on Dynamic Tetrahedral Boronate-Esters Bonds and Hydrogen Bonds

Abstract

Although some studies have reported high-toughness or high-strength self-healing materials, the self-healing process still requires demanding conditions such as high temperatures. It remains challenging to achieve a balance between mechanical properties and self-healing efficiency under mild conditions. Herein, we design a novel self-healing polyurea-urethane (PUU) material. The polymer has crosslinked internal “cores” and well-designed flexible chains with multiple alicyclic structures, which are crosslinked via tetrahedral boronate-esters bonds (TBEs) and hydrogen bonds, resulting in a dynamic crosslinked PUU network (denoted as TBE-PUU). The resulting materials (TBE-PUU₂) not only exhibit outstanding tensile strength (28.5 MPa), stretchability (1217%), toughness (166.1 MJ m⁻³), etc., but also possess excellent self-healing ability in response to water or thermal stimuli. It achieves high self-healing efficiency of 92.0% at room temperature for 48 h with the aid of water and 97.7% at 60°C for only 8 h. The new strategy offers new possibilities to seek a balance between material dynamic properties and mechanical robustness.