Mechanically robust self-healing and recyclable flame-retarded polyurethane elastomer based on thermoreversible crosslinking network and multiple hydrogen bonds

Self-healing polymers have drawn significant attention because of their great potential for applications in many fields. It is highly desirable to prepare materials capable of self-healing and with excellent mechanical properties. Additionally, the flammability of polymers make them unsafe during use. A novel strategy is proposed to manufacture a multifunctional polyurethane elastomer with high tensile strength (37.11 +/- 1.89 MPa) and excellent self-healing efficiency (91.8%), containing a thermo-reversible crosslinking network and multiple hydrogen interactions. The furan-terminated phosphorus-based monomer, tri(2-furyl) phosphoramide (TFP), was successfully synthesized and then conjugated into a maleimide-terminated linear segmented polyurethane (MPU) backbone to prepare self-healing, recyclable, and flame-retarded polyurethane (MPUF). Due to its synergetic dual reversible bonds, the multifunctional polyurethane elastomer possessed ultrahigh strength, and excellent self-healing, shape recovery, and reprocessing properties. The phosphorus containing polyurethane elastomer exhibited improved thermal stability a limiting oxygen index value of 28.5%, and a 12.3% decrease in the peak heat release rate (pHRR) relative to those of unmodified polyurethane. This work demonstrates an effective strategy to prepare multifunctional polyurethane elastomer with both high self-healing efficiency and excellent mechanical properties allowing application for this material in the fields of fire-control coatings and building materials.