Smart anticorrosion coating based on stimuli-responsive micro/nanocontainer:a review

Smart coating for corrosion protection of metal materials(steel,magnesium,aluminum and their alloys)has drawn great attention because of their capacity to prevent crack propagation in the protective coating by releasing functional molecules(healing agents or corrosion inhibitors)on demand from delivery vehicle,that is,micro/nanocontainer made up of a shell and core material or a coating layer,in a controllable manner.Herein,we summarize the recent achievements during the last 10 years in the field of the micro/nanocontainer with different types of stimuli-responsive properties,i.e.,pH,electrochemical potential,redox,aggressive corrosive ions,heat,light,magnetic field,and mechanical impact,for smart anticorrosion coating.The state-of-the-art design and fabrication of micro/nanocontainer are emphasized with detailed examples.

Developing single-atom catalyst-based epoxy coating with active nanocatalytic anticorrosion performance in oxygen environment

The stimuli-responsive anticorrosion coatings have drawn great attention as a prospective corrosion protection approach due to their smart self-repairing properties.In contrast to passive protection mechanism based on post-corrosion microenvironmental changes,a unique active protection strategy based on nanocatalytic oxygen depletion is proposed in this work to inhibit the occurrence of corrosion.Porous FeeNeC catalysts with outstanding oxygen reduction reaction(ORR)activity(half-wave potential of 0.89 V)is firstly synthesized through pre-coordination with organosilane precursor to obtain homogeneously distributed active sites.When this catalyst is introduced into the coating matrix,uniformly distributed FeeNeC not only compensates the defects but plays a crucial role in adsorption and consumption of diffused oxygen in the coating.Under this dual action,the penetration of corrosive medium,especially oxygen,through coating to metal substrate is greatly suppressed,resulting in effective corrosion inhibition and a significant increase in corrosion resistance of the composite coating compared to pure epoxy coating.This work provides a new perspective and the starting point for the design of high-performance smart coating with active anticorrosion properties.

Active anticorrosion and self-healing coatings:A review with focus on multi-action smart coating strategies

The development of smart coatings with potential for active anticorrosion and self-healing protection of metals is essential for long-term performance of metallic structures in aggressive chemical environments.Presently,emphasis has been placed on the development of advanced smart coatings for corrosion protection in different applications.Innovative multifunctional coatings with fascinating stimuliresponsive functionalities are considered“smart”.The stimuli-responsive functionalities of these smart coatings when properly harnessed result in a class of coatings with inherent autonomous control of corrosion.Fundamentally,when metals are exposed to aggressive environments,occurrences at the metalsolution interface cause environmental changes.These changes can be controlled when triggers from external environment set off active components of smart coating,thereby enhancing coating’s life and functionality.Common triggers include the availability of moisture,concentration of chloride ion,p H gradient,mechanical damage,impact,fatigue,light,redox activity and temperature.In this review,recent technological trends in active anticorrosion and self-healing coatings as functional routes for metal protection are summarized,stimuli responsiveness and mechanisms of inhibition are discussed,and recent multi-action protective systems are particularly focused on.

A Self-Strengthening Epidermis-Like Smart Coating Enabled by Dynamic Iron Sequestration

Living organisms rely on materials sequestration from the environment to strengthen their bodies.Such constant activity provides necessary supplies for critical biological functions,which is difficult by man-made structures due to the lack of a dynamic sequestration mechanism.In this study,it is shown that an epidermis-like smart coating can respond to changes in salinity to allow a spontaneous and progressive strengthening when supported by steel as a sustained iron source.The self-strengthening is enabled by reaction-coupled diffusion,which makes possible the dynamic sequestration of iron from the in situ rusted steel,partially mimicking the iron accumulation process in a mussel.The emergence of iron-phenolic coordination bonds continuously improves modulus,hardness,and adhesion,achieving a strengthening efficiency comparable to mussel byssus.Interestingly,the bilayer design ensures long-term self-healing performance even during strengthening and a mechanically robust anticorrosion coating with an autonomic protection mechanism and gradually enhanced barrier properties during prolonged service.Our results provide a new venue for the design of stimuli-responsive smart materials characteristic of an open biological system and may serve as the basis for creating highly intelligent devices with sophisticated functionality.