Carbon-nanotube-filled catalyst-free thermoset polyurea composites towards achieving recyclability, weldability and permanent shape reconfiguration

Integration of the advanced functionalities of recyclability, weldability and permanent shape reconfiguration into traditional thermoset polyureas is particularly attractive; however, it is still challenging to achieve. In this study, we successfully synthesized carbon-nanotube-filled catalyst-free thermoset polyurea composites based on hindered urea bonds to achieve the abovementioned functionalities in one polymer network via multiple stimuli. Via the incorporation of CNTs into the pristine thermoset polyureas without a catalyst, significant mechanical robustness, excellent reprocessability by hot press or micro injection and preeminent weldability using heat or near-infrared (NIR) irradiation could be achieved. Especially, the original shape could be reconfigured into various complex permanent shapes under heat or NIR irradiation. Subsequently, the new permanent shape could be further used to conduct elastic shape memory experiments. Thus, the combination of elastic shape memory and permanent shape reconfiguration can broaden the applications of complex multifunctional shape-memory polymers.