Design,Preparation And Properties Of Dual-action Self-healing Anticorrosion Coating Based On Nanofiber Film

As a pervasivly destructive erosion phenomenon,metal corrosion has caused enormous economic lossesandseveresafetyconcerns.Intelligent self-healing anticorrosion coatings that could automatically sense corrosion damage,followed by actively inhibit corrosion activities or spontaneously restore coating defects with minimum external intervention,have largely prolonged the service time of metal materials and significantly broaden their anticorrosion application.According to the difference of repair mechanisms,smart self-healing anticorrosion systems can be divided into two categories: corrosion inhibitor-based self-healing strategy and coating bulk recovery,targeting to forming active protective film and reestablishing passive barrier performance respectively,to inhibit corrosion spread.Forinhibitor-basedcoating,the loading of corrosion inhibitor in coating is limited,and the formed protective film is susceptible to damages from corrosion environments.Hence,inhibitor-based self-healing strategies cannot accomplish large-scale self-healing and long-term corrosion protection effects.As for coating bulk repair technique,externally triggered healing behavior and relatively slow healing procedures readily generate severe early corrosion issues,seriously hindering their practical application and the development of repair technique.Therefore,an ingenious combination of active corrosion inhibition based on corrosion inhibitors and coating passive barrier recovery capability was proposed in this article,through a facile electrospinning technique.Composite coating anticorrosion efficiency was greatly enhanced from two aspects of immediate corrosion suppression and repairing shielding effect,endowing the coating with synergetic dual-action self-healing ability.Main works are as follows:1.A nanofiber-supported composite coating with both active corrosion inhibition and self-healing capability was fabricated on metal substrate for corrosion protection.Polycaprolactone(PCL)nanofiber embedded with corrosion inhibitor nanocontainers was deposited on metal surface by electrospinning,forming a dual-functional nanofiber network framework,followed by infiltrating epoxy protective layer.Encapsulated corrosion inhibitor 2-mercaptobenzothiazole(MBT)released in a p H-controlled manner and inhibited early corrosion activities immediately.Meanwhile,the thermal-initiated liquidity of PCL nanofiber could repair coating damage effectively,recovering coating passive barrier performance.Additionally,depending on the interconnected internal structure of PCL nanofiber,healing agents can be continuously transformed from rich-part to depleted-region to achieve repeatable self-healing.The anticorrosion performance was well maintained even after three cycles of healing.Repaired coating exhibited desirable anticorrosion effect,mainly attributing to the synergetic repair behavior of forming active protective film and recovering passive barrier.This self-healing anticorrosion system will show great potential in long-term corrosion protection.2.A composite coating with both corrosion self-reporting and accurately controlled self-healing behavior under near infrared(NIR)irradiation was developed through graphene oxide(GO),corrosion inhibitor 8-hydroxyquinoline(8HQ)and PCL nanofiber.The presence of GO endows the coating with stable,fast photothermal conversion capacity.PH changes caused by corrosion reactions could automatically trigger the release of 8HQ in corrosive regions,followed by coordinated with metal ions.The formed protective layer plays a double role in this system:(1)acting as corrosion inhibitors to inhibit corrosion reactions immediately;(2)exhibiting obvious fluorescence enhancementafter interacting with metal ions,warning early corrosion phenomena.Corrosion site can be located accurately under remotely controlled NIR,with the aid of corrosion self-reporting property of 8HQ.Under the irradiation of NIR,the temperature of localized area improved quickly,liquefying PCL nanofiber to achieve fast self-healing behavior within 5 min.This multifunctional anticorrosion system integrates corrosion self-reporting,precise positioning and dual-action self-healing behavior,implementing timely and accurate healing treatment for corroded regions,providing a promisingidea for the development of a new generation of intelligent anti-corrosion coating.