Study On The Preparation Of Smart Hollow Mesoporous Zirconia Nano-containers And Its Application In Anti-corrosion Coating

Nanocontainer is a new concept proposed in rencent years with the basic skeleton character of a core-shell structure. Zirconium dioxide (ZrO2) is one of the most thermostable oxides and has become a research hotspot in material fields. Study on the preparation of the hollow mesoporous ZrO2 with the features of smaller density and greater loading capacity is relativity few. However, the features mentioned is necessary for the use of ZrO2 as a nanocontainer. The key of our work is to prepare the hollow mesoporous ZrO2 microspheres (HMZSs), The hollow microspheres made by traditional hard-template method are easily broken and hardly molding. In this paper, the stable and controllable HMZSs were prepared successfully with sol-gel method.Meanwhile, the research of adsorbing the inhibitor into the cavity of the smart nanocontainer, and then doping it into the basecoating to form a smart anti-corrosion coating with self-healing ability has become a hot topic in the field of anti-corrosion. According to the theory of electrical neutralization, the HMZSs with negative charge can absorb gust molecules with positive charge into its hollow interior to build a smart nanocontainer system under neutral conditions. Based on the different isoelectric points, the two molecules with different charges under the different pH conditions will attract or repel each other. The interaction in smart nanocontainer system will take the action of " zero or weak release " or " rapid and massive release "for the absorbed guest molecules under different pH conditions, thus reaching a pH-controlled release condition.The effects of metal corrosion are getting worse. Nowadays, one of the main methods against the corrosion is coating a layer of anti-corrosion on the metal surface. Though traditional chrome-coatings have a good repair effect, it will produce the hexavalent chromium pollution. So, it is gradually being replaced by smart anti-corrosion coating with the characteristics of environment friendly and self-healing. Generally, the smart anti-corrosion coating which has self-healing capabilities consists of two parts:the first part is the negative coating which plays a role of a physical barrier; the second part is the smart nanocontainer loaded with inhibitor molecules, dispersed uniformly in passive coating, and with a quick respond to external environment. When the coating is damaged, the pH value of the micro anode and cathode region in the damaged location will be changed. Dope the pH-controlled release system into the waterborne epoxy coating, and then coat the coating to the metal surface. When pH changes, the inhibitor molecules would be released, thus decreasing the corrision and achieving the performance of the self-healing effect. There is no doubt that the smart nanocontainer play a key role in the whole system. The different structural has different pH-controlled release effects, thus making corresponding effects on the anti-metal corrosion protection.