Hard, tough and fast self-healing thermoplastic polyurethane

Its necessary to develop self-healing polymers, which will significantly improve the safety and service life of artificial materials. Although extensive research efforts have been devoted to the field, it is still a challenge to synthesize hard and tough polymers, which own self-healing ability under mild conditions. In this work, we fabricated a hard and tough thermoplastic polyurethane (TPU, PCL-HM) and the wound of PCL-HM can be quickly healed under mild conditions (50 degrees C). Comprehensive characterization results suggest that the Young's modulus, tensile strength and elongation at break of PCL-HM can reach 76 MPa, 11.8 MPa and 841%, respectively, which is better than most recently reported TPUs. PCL-HM prepared with aromatic disulfide bonds as dynamic covalent bonds, polycaprolactone diol (PCL 2000) as soft segment, isophomne diisocyanate (IPDI) and dicyclohexylmethane-4,4'-diisocyanate (HMDI) as hard segment, can quickly recover to 92% of its original tensile strength within 1 h at 50 degrees C. Due to the better segment movement and looser packing of aromatic disulfide in PCL-HM, the PCL-HM displays better healing properties compared with other types of TPUs (PCL-I, PCL-H, PCL-M, PCL-HM') prepared in this work. In addition, the fast healing properties of PCL-HM under mild conditions endow it with great application prospects in the field of protective coatings. The successful preparation of PCL-HM also provides a new idea for the synthesis of hard and tough TPU.

Automated summary

The study successfully prepared a hard and tough thermoplastic polyurethane material PCL-HM with self-healing abilities, which can quickly heal wounds under mild conditions. By using aromatic disulfide bonds as dynamic covalent bonds and incorporating IPDI and HMDI in the hard segment, PCL-HM displays better healing properties compared to other types of TPUs.