Self-healing supramolecular waterborne polyurethane based on host–guest interactions and multiple hydrogen bonds

Polymers which contain 2-Amino-4-hydroxy-6-methylpyrimidine (UPy) usually show good self-healing capabilities under certain conditions. In this study, the UPy was grafted into the side chain of waterborne polyurethane (WBPU), which was synthesized from 4,4-diisocyanate dicyclohexylmethane (H12MDI) and polycarbonate diol (PCDL), for giving the function of self-healing to the polymer. Meanwhile, the methylated β-cyclodextrin (M-β-CD), which was able to enhance the mechanical properties of WBPU and realize the synergistic effect between M-β-CD and UPy to raise the performance of self-healing, was introduced onto the main chain of WBPU. The Tg (glass transition temperature) of the polymer can be observed from dynamic mechanical property analysis (DMA) below room temperature, which facilitated the movement of the chain in self-healing process. From the tensile test, it showed that the cut polymer spline displayed a self-healing efficiency of 92.29% at 100 °C within 36 h. Furthermore, the disappearance of surface scratch of polymer film was observed by heating under a polarized microscope (POM) with a heating table. The results manifested that SWBPU exhibited great application as an intelligent response-type material.