Micro/nanocontainer-based intelligent coatings: Synthesis, performance and applications - A review

Metal corrosion causes huge economic losses, environmental pollution and industrial disasters. Application of smart self-healing coatings for the active corrosion protection of metal substrate has attracted substantial interest in recent years. The self-healing function can be achieved through either the intrinsic or extrinsic method. The intrinsic self-healing coatings mainly make use of the reversible physical and chemical interactions between molecules, whose self-healing effect is permanent. While the extrinsic method is mainly caused by embedding the micro/nanocontainers in the coatings, which can sense the micro-environmental changes and give rapid feed-back to repair the micro cracked zones on the coating surface, the self-healing performance is temporary after the encapsulated active substances are fully consumed. Furthermore, inspired by these intelligent behaviors, more and more multi-functional coatings are designed and widely used in different fields. In this review, we sum-marized the research development of different stimuli-responsive self-healing coatings based on micro/nano-container techniques in recent years. Different types of micro/nanocontainers, as well as their synthesis or encapsulation technologies, are exampled to clarify the recent achievements. Meanwhile, the single stimulus-responsive systems are gradually evolved into the multi-stimulus-responsive system that endows the coatings with more sensitivity and intelligence. The stimuli-responsive self-healing coatings with different functions, such as self-reporting, anti-microbial, anti-fouling and self-lubrication functions, etc., are also explored, which en -riches the application ranges of these smart coatings. This review investigated the research progress of the micro/ nanocontainers-based self-healing coatings over the past few years and provided a unique insight into the future development of such smart coatings.