Bioinspired extremely rapid self-repairing coatings for long-life repeated features

Abstract

Emerging materials capable of self-repair to damaged areas are attracting attention for environmental protection and energy reduction. Although coatings whose material elasticity physically restores surface-dents are in practical use, in the case of crack damage, they cannot perform their self-repairing function. Conversely, coatings that exhibit the capacity to repeatedly repair themselves chemically have been challenged by long repair times. Here water-induced, self-repairing coatings inspired by cephalopod self-healing mechanisms were developed that can ultra-rapidly repair surface scratches. The introduction of counter-ions into polyelectrolyte multilayers produced coatings mimicking the strong β-sheet structures, noncovalent intermolecular interactions, and consequently self-repair process in cephalopods. These features resulted in a decrease in the strong polycation–polyanion electrostatic bonds and an increase in the noncovalent polymer networks. Furthermore, counter-ion addition improved the coating’s water absorption and retention properties. The ion-trapped polymer networks facilitated expansion in the horizontal direction where a scar was present, resulting in ultrafast self-repairing rate of 92% in 1 s and 100% in 10 s. These extremely rapidly self-repairing coatings have various potential applications given knowledge acceleration via machine learning. The key technology developed here paves the way for novel insights into the construction of self-repairing materials and contributes to the development of a sustainable society.