A facile strategy for multiple dynamic polyurethane with high mechanical strength, room-temperature healability and recoverability

The introduction of self-healability and recoverability into widely used polymer materials such as polyurethane has become an important way to increase their service lifetime and decrease the amount of waste to solve the pollution problems. However, it remains a formidable challenge to integrate robust mechanical properties with room-temperature self-healability and recoverability due to the proverbial trade-off between robustness and flexibility of polymer chains. In this study, a kind of multiple dynamic polyurethane (MDPU) consisted of dynamic acylsemicarbazide bonds and disulfide bonds as well as multiple hydrogen bonds derived from acylsemicarbazide bonds was readily prepared by the reaction between 3,3 '-dithiodipropionate as multifunction chain extender and an isocyanate-terminated prepolymer. The chain structures and physicochemical properties were fully investigated. The results demonstrated that colorless transparent MDPU can not only possess high strength (>17 MPa), high stretchability (>700 %) and high toughness (>57 MJ & sdot;m(-3)), but also exhibit a high selfhealability (healing efficiency over 70 % at 25 degrees C under the assistance of drops of N, N-dimethylformamide) and a good recoverability (almost completely recovered after thermocompression at 110 degrees C for 1 h). Considering the cheap and widely available resource and facile synthesis process, the strategy designed herein also provides a promising and cost-effective approach to readily fabricate self-healable polyurethane with desirable multifunctionality.