Advanced multifunctional self-healing composites for the integration of wear resistance and damage monitoring

Abstract

The inherent conflict between self-healing and wear resistance has long been a key issue in materials science. Driven by the goals of economic and social sustainability, we are committed to finding an ideal balance between these two seemingly opposing properties through molecular structure design and reinforcement optimization. On this foundation, we have innovatively integrated damage monitoring into the coating material. Herein, an advanced multifunctional waterborne polyurethane-based composite coating (BNC-SWPU) was constructed for the first time by innovatively combining self-healing, wear resistance and damage monitoring. These properties were conferred by a design strategy that combined modified boron nitride nanosheets/carbon quantum dots (BNON/CQD) hybrid fillers with multiple dynamic reversible bonds (disulfide and hydrogen bonds). BNON/CQD fillers synergistically enhanced the wear resistance of coatings through the interlayer slip of BNON and the nano-bearing-like structure exhibited by CQD at the sliding interface. Meanwhile, the composite coatings possessed excellent self-healing ability under both scratch and wear due to the easy migration of molecular chains and the capability of the dynamic bonds to break and reform in response to thermal stimuli. The composite coatings, due to the introduction of CQD with fluorescent properties, were endowed with an intense blue emission capability under UV light. Upon damage, emission intensity diminished but recovered post-self-healing. Consequently, this innovative design provides new ideas for the development of smart materials, while the multifunctionality it gives to composite coatings shows great potential for practical applications.