Preparation of Room-temperature Self-healing Recyclable Polyurethane Elastomers Based on Multiple Hydrogen/Nitrogen Coordination Boro-oxygen Bonds System

Polyurethane elastomers have excellent tensile properties and elastic recovery properties, but traditional polyurethane elastomers are often broken and irreparable due to wear, so the research on high strength self-healing polyurethane elastomers has broad application prospects. In this study, based on the concept of intrinsic self-healing, multiple hydrogen bonds and boroxane rings with N-B coordination bonds were designed into the molecular. A novel polyurethane elastomer was prepared by four-step addition of polytetrahydrofuranediol, isophorone diisocyanate, 4,4'-methylene bis(2-chloroaniline), 2-formylphenylboric acid, toluene, N, N-dimethylacetamide and 2, 6-pyridinediol. The prepared elastomers exhibit strain-induced strengthening and have excellent self-healing properties as well as excellent mechanical properties. When the molar ratio of PDM/MOCA is 60/40(PU _HB-60/40 ), the tensile strength of the material is 18.8 MPa (self-healing efficiency 94.7%), and elongation at break is 2132% (self-healing efficiency 91.7%), and toughness is 117.0 MJ·m ^-3 (self-healing efficiency 86.7%). Synchronous self-healing efficiency exceeds 86%. In addition, the elastomer also has the ability to be recyclable, and the change of mechanical properties are slightly before and after dissolution and reshaping. This study provides beneficial ideas for preparing room temperature self-healing recyclable polymers with high strength.