Base-Layer-Driven Self-Healing Materials

Despite the enormous potential applications for intrinsic self-healing materials, these materials have reached a road-block where concurrent excellent mechanical properties and autonomous self-healing behavior are impossible. Herein reported is a base-layer-driven self-healing (BLDS) approach that facilitates self-healing irrespective of the glass transition (Tg) or melting temperature (Tm) of the top layer. The BLDS approach enables autonomous self-healing materials that concurrently offer ultramechanical durability and ambient healing. The BLDS relies on an ambient healable base layer and a structural/functional top layer. In this study, the bottom layer is prepared using reversible-dynamic covalent linkages in polyurethane/urea. Meanwhile, the top layer is selected from a thermoplastic (e.g., polylactic acid), thermoset (e.g., polyurethane), and functional thermosets (e.g., omniphobic urethane). The resultant dual-layer coatings/films offer a modulus of >800 MPa and still maintained excellent ambient self-healing. The antirust efficacy of the BLDS coating is also demonstrated. As the top layer can be selected from any commercial structural and functional materials, this work opens a whole different direction for autonomous healable materials, which will open additional avenues of real-world applications.