Enhanced Multifunction in Polyurethane Elastomers via Regulation of Triple-Crosslinked Network With Dynamic Covalent and Noncovalent Bonds

Self-healing polyurethane elastomers with dynamic crosslinking networks are promising candidates for intelligent next-generation coatings. However, their constitutive relation shows conflicts between high mechanical performance and room-temperature self-healing, as well as recyclability. Here, a regulation strategy of a dynamic triple-crosslinked network in the hard domain was proposed to achieve multifunction enhancement via covalent borate ester bonds coupling noncovalent. The distribution and ratio of borate ester bonds, boron-nitrogen coordination bonds, and multiple hydrogen bonds were meticulously designed to balance fracture and reconstruction of the molecular network. The introduced borate ester bonds enabled the basic room-temperature self-healing and mechanical performance of polyurethane elastomers through molecule-level topological evolution. The designed boron-nitrogen coordination bonds and abundant hydrogen bonds provided external noncovalent reversible crosslinking networks, thus improving tensile strength and toughness as physical crosslinking points. The obtained polyurethane elastomers exhibited impressive light transmittance of 93%, a tensile strength of 41.07 MPa, elongation at break of 1673.20%, toughness of 166.74 MJ m −3 , and almost entirely room-temperature self-healing in 48 h. These polyurethane elastomers even maintained 90% of their original mechanical properties after suffering three recycles. This strategy may promote the practical application of intelligent self-healing polyurethane coatings in the automobile and flexible electronic industry.