The dynamic chain effect on healing performance and thermo-mechanical properties of a polyurethane network

Dynamic covalent chains that composed of three or five dynamic polyurea bonds are introduced into cross-linked polyurethane to overcome the classical dilemma between healing rate and thermo-mechanical properties. Comparing with dynamic urea bond, the incorporation of the dynamic polyurea chains with multiple leads to significantly improved thermo-mechanical performance and healing rate/efficiency on the network. Remarkably, several folds' increases in tensile and adhesion shear strength as well as 53 °C enhancement in glass transition temperature are achieved without sacrificing the material properties of the polyurethane network. We attribute the improvements to the decomposed polyurea chain segments, which have higher diffusivity and larger quantity than the dynamic urea bond that tied in the control network. This study provides a concept of dynamic covalent chain to address the classical dilemma between healing performances and thermo-mechanical properties among healable thermosets .