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

Polyurea has gained increasing attention in civil engineering, flexible electronics, and other emerging fields. However, owing to the rapid polymerization, tailoring their mechanical properties of polyurea for different applications remains challenging. Herein, a novel strategy is proposed for the insertion of urea moieties to prepare one-component robust, mechanically tunable, and healable polyurea. First, the prepared latent curing agent, isophorone diisocyanate (IPDI), and NCO-terminated prepolymer (PPGTD) are mixed. Due to the large difference in the reactivity of the NCO groups in IPDI and PPGTD, IPDI first reacts with the deblocked amino groups 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, the as-prepared polyurea exhibits excellent self-healing, impact resistance, high transparency (>90%), and high dielectric constant (approximate to 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.