Title：Insertion of Urea Moieties for One-Component Strong yet Tough, Self-Healing Polyurea Protective Materials

Abstract: Polyurea has found applications in civil engineering, flexible electronics and other emerging fields because of its excellent quasi static mechanical properties and strain–rate–dependent behavior. However, owing to the rapid polymerization, tailoring their mechanical properties of polyurea for different applications remains challenging. Herein, we propose a novel strategy for the insertion of urea moieties to prepare one-component robust, mechanically tunable, and healable polyurea. First, the prepared latent curing agent, isophorone diisocyanate, and NCO-terminated prepolymer are mixed. In the presence of moisture, isophorone diisocyanate first reacts with the amino group to form continuous urea moieties. The resulting urea moieties are inserted into the polyurea. This strategy provides a tremendous improvement in strength (500% increase), storage modulus (532% increase), and toughness (281% increase). Additionally, polyurea prepared via this method exhibits excellent self-healing, impact resistance, high transparency (>90%), and high dielectric constant (~4.5). Thus, it can be used as a protective film and flexible substrate for electronic devices. Furthermore, the polyurea exhibits good versatility, which can be laminated with alumina ceramic sheets to form impact composites. This work opens up a promising avenue for the design and fabrication of polyurea material for flexible electronics and provides new insights into engineering anti-impact materials.

DOI：10.1002/adfm.202310603