Study On The Preparation And Application Of Two-component Self-healing Microcapsules

Metal corrosion and the resulting material damage and economic damage have become a worldwide issue.One of the easiest and most common ways to protect metallic material against corrosion is the application of organic coatings,such a coating layer can form a physical barrier to prevent contact between the metal surface and the corrosive environment(air,oxygen,and water).However,organic coatings are always subjected to mechanical damages and cause the failure of coatings.And the concept of self-healing coating has been proposed to act as a quick remedy for mechanical damages.Hence,there are great application prospect about self-healing coating in the field of anti-corrosion.Dual-component microencapsulated hydrophobic amine and microencapsulated isocyanate were designed and fabricated for self-healing anti-corrosion coating.In this system,novel hydrophobic polyaspartic acid ester(PAE)and isophorone diisocyanate(IPDI)were microencapsulated respectively with melamine-formaldehyde(MF)as shell via in situ polymerization.The synthesis process of dual-component microcapsules and the surface morphology,chemical structure and thermal stability of microcapsules were characterized by optical microscopy(OM),field emission scanning electron microscope(SEM),fourier transform infrared spectroscopy(FTIR)and thermogravimetric analyzer(TGA).In order to optimize the preparation process and improve the product quality,IPDI microcapsules were fabricated by changing the core/shell ratio,emulsifier concentration and emulsification rate.Results showed that the optimum core/shell ratio of this experiment is 3:1,the suitable emulsifier concentration is 2.52 wt%,and the diameter of IPDI microcapsules ranged of 2.66?11.25 ?m are manufactured by adjusting emulsification rate over the range of 3000?9000 rpm.Besides,in order to improve the stability of the PAE emulsion,urea,tung oil and aqueous isocyanate were separately added during the preparation of PAE microcapsule.Results also showed that isocyanate can form a polyurea(PU)chemical barrier on the surface of the emulsion droplet and protect the stability of emulsion,the diameter of PAE microcapsule with MF/PU shell is 4.20 ?m,and the optimal addition amount of isocyanate aqueous solution is 15 wt%of core material.In addition,the application of self-healing microcapsules was studied preliminarily in this paper.The dual-component microcapsules were embedded in epoxy resin matrix coating,and then coated the prepared self-healing coating onto metal surface.SEM,true color confocal microscope(TCCM)and electrochemical workstation were used to investigate the self-healing and corrosion resistance performances of epoxy composite coatings.Results indicated that epoxy coatings display well self-healing and anti-corrosion properties,and the optimal addition amount of microcapsules is 15 wt%.