Synergistic Enhancement of Polyurethane Materials by Dynamic Borate Bonds and Inorganic Nanoparticles

This study reports on a polyurethane nanocomposite containing dynamic borate bonds (containing boron and nitrogen endocoordination) with three different nanoparticles as reinforcing fillers. First, a bis-boron nitrogen coordinated borate ester bonded diol (TB–OH) was synthesized and introduced into the polyurethane prepolymer as a chain extender, followed by the addition of a cross-linking agent to form a reticulated cross-linking structure, and finally, the nanoparticles were dispersed into the polymer matrix by the blending method. Among them, the TB-Ca sample had a maximum tensile strength as high as 15.23 MPa, which was 529% higher than that of TB-0, and the Td5% experienced an elevation from 234 to 275 °C. It also showed excellent self-healing performance, achieving a self-healing rate of 83.53% and up to 12.69 MPa when repaired.