Sustainable Thermosetting Polyurea Vitrimers Based on a Catalyst-Free Process with Reprocessability, Permanent Shape Reconfiguration and Self-Healing Performance

Traditional thermosetting polyureas (TPUs) with eminently comprehensive performance have been used in a variety of industrial applications. However, they suffer from a certain intractable difficulty in achieving multiple functions such as reprocessability, shape reconfiguration, or self-healing performance due to the extremely stable covalent cross-linking. Herein, we employ hindered urea bonds (HUBs) as a reversible dynamic covalent cross-linkage to design catalyst-free hindered thermosetting polyureas (HTPUs). By incorporating HUBs into TPUs, the synthesized HTPUs can be reprocessed by using hot press or microinjection technique without any catalyst. In addition, those obtained materials have achieved great abilities of permanent shape reconfiguration and self-healing. Especially, the combination of the conventional elastic shape memory with the solid-state plastic shape reconfiguration in these HTPUs will broaden the geometrically complex shapes for shape memory polymer. Importantly, introducing longer and more bulky substituents into HTPUs can simultaneously endow the materials with excellent mechanical properties and the aforementioned multiple functions. Despite what is mentioned in this article, more potential HTPUs with excellent mechanical properties and multiple functions could be further designed by introducing longer and more bulky substituents into the formal polymers.