Self-healing thermoset polyurethanes utilizing host?guest interaction of cyclodextrin and adamantane

Self-healing polyurethane network films driven by cyclodextrin/adamantane host-guest interaction were prepared by the urethanization reaction of glycerol ethoxylate (GCE), ?-cyclodextrin (?-CD), and 1-adamantanol (AdOH) with hexamethylene diisocyanate (HDI). The effects of feed monomer ratios on the thermal, mechanical, and healing properties were investigated. The results of Fourier transform infrared spectroscopy and gel fraction measurements confirmed the formation of polyurethane networks. The glass transition temperatures (Tgs), tensile strengths, and tensile moduli of the network films decreased with increasing GCE content. The Tgs and tensile moduli increased with increasing feed NCO/OH ratio from 0.6 to 1.0. We could not find a significant effect of the ?-CD/AdOH ratio over the range of 1/1?1/4. All the network films prepared from GCE, ?-CD, AdOH, and HDI showed healing properties at room temperature, whereas the corresponding film without AdOH did not. The healing efficiency increased as the ?-CD/AdOH (1/1) content increased and the NCO/OH ratio approached 1.0.