Self-healing polyurethane elastomers based on boroxine ring/hydrogen bond dual dynamic networks: Preparation, properties, and molecular simulations

Self-healing polyurethane elastomers with dynamic crosslinking structures possess great potential for functional development. However, most existing studies focus on the regulation of macroscale properties, lacking in-depth microscopic analysis of crosslinked networks, which makes it challenging to elucidate the synergistic mechanism between mechanical and self-healing properties. Herein, modified polyurethane was used as the matrix, and tannic acid (TA) was introduced to construct PU-HPBA/TA self-healing elastomers crosslinked by a synergistic network of boroxine rings and multiple hydrogen bonds. Systematic studies were conducted by combining macroscale structural and property characterization with molecular dynamics (MD) simulations. The results show that TA can effectively optimize the crosslinked network. The sample with a TA content of 4.4 wt% exhibits the optimal mechanical properties, with a tensile strength of 9.22 ± 0.32 MPa, an elongation at break of 882.4 ± 47.6%, and a self-healing efficiency of 79.3 ± 3.2%, achieving a balance between structural stability and self-healing ability. MD simulations reveal dynamic evolution behaviors of three distinct hydrogen bond species at the microscopic level, confirming that PU-TA hydrogen bonds dominate the system, which provide microscopic insights into polyphenol-modified boron-based self-healing elastomers. This study provides a new strategy for the design of self-healing polyurethanes, and molecular simulations offer microscopic support for the mechanism research of dynamic bond self-healing systems, while expanding the application prospects of bio-based polyphenol-modified elastomers.