Fast (Re)processing of Urea-Containing Polymers Enabled by Dynamic Aminoketoenamide Bonds

Abstract

This work presents a straightforward strategy to introduce dynamic covalent aminoketoenamide (AKE) onto the backbone of polyurea-based polymers. Bis-vinylogous amides were synthesized from diamines and acetylacetone and used as drop-in agents during the polymerization of compounds featuring amine, hydroxyl, and isocyanate reactive groups. This chemistry leads to AKE-containing poly(urea urethane)s (PUUs) that are thermally healable and reprocessable due to the dissociation of AKE at elevated temperatures. The obtained PUUs displayed faster stress relaxation rates and lower activation energies upon increasing the AKE content, which favored fast processing. Moreover, the ability to act as a hydrogen-bonding acceptor of the two carbonyl groups of the AKE moiety allowed us to toughen the PUUs. Given the facile synthesis of AKE, this method opens a promising route toward recycling and toughening urea-containing polymers on large scales.