The self-healing cross-linked polyurethane by Diels-Alder polymerization

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 degrees C and the r-DA reaction occurred at 109.5 degrees C. This cross-linked polyurethane shows a remarkable high hardness (shore D80). When preserved at 80 degrees 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 degrees C for 12 hr, the self-healing efficiency was 67.56%.