The self‐healing cross‐linked polyurethane by Diels–Alder polymerization

Abstract Polymer materials containing Diels–Alder (abbreviated DA ) groups show good self‐healing ability under certain conditions. In this study, the thermal reversible DA bond was introduced into polyurethane by the design of molecular chain to obtain the self‐healing properties. The pre‐polyurethane ( HTK ) end‐capped with furan rings was synthesized by hexamethylene diisocyanate trimer and furfuryl alcohol firstly. Then, HTK was mixed with bismaleimide (BMI) to synthesize the cross‐linked polyurethane HTK‐PU. Finally, the properties of the HTK‐PU were characterized. It can be observed from DSC that the DA reaction occurred at 76°C and the r‐ DA reaction occurred at 109.5°C. This cross‐linked polyurethane shows a remarkable high hardness (shore D80). When preserved at 80°C for 6 hr, the self‐healing efficiency of the HTK ‐ PU was 53.75% known from tensile test, and cracks on it virtually disappeared as observed from polarizing microscope ( POM ). When preserved at 80°C for 12 hr, the self‐healing efficiency was 67.56%.