Preparation Of Polyaniline Hybrid Shell Microcapsules And Anti-corrosion Performance Of Self-healing Coating

Metal corrosion has become an important problem hindering production and life,and has brought huge losses to the national economy.At present,the effective anti-corrosion measure is to coat the metal surface.The coating is easy to be affected by external force in the process of application,resulting in micro cracks which are difficult to repair.Microcracks reduce the corrosion resistance of the coating,even accelerate the peeling of the coating and accelerate the corrosion of the metal.How to use coating self-healing technology to effectively protect metal has become a research hotspot in the field of coating protection.According to the research at home and abroad in recent years,microencapsulation technology is widely used as a self-healing method;as the filler of anticorrosive coating,conductive polymer can improve the anticorrosion performance significantly.Researchers have done a lot of research on both sides and achieved good results,but there are few studies on the combination of both sides.In this paper,the conductive polyaniline self-healing microcapsule is proposed.Through the synergistic effect of the self-healing agent and conductive polyaniline,the polymer coating has good corrosion resistance to the steel substrate.The mechanism of the synergistic corrosion resistance of the core material and the shell material is revealed,which has important reference value for the realization of metal corrosion resistance and industrial application.（1）Using isophorone diisocyanate as core material,polyurethane and polyaniline as shell materials,self-healing microcapsules were successfully prepared by interfacial polymerization and in-situ polymerization.By discussing the types of emulsifiers,the concentration of emulsifiers,types of synthetic polyurethane monomers,the homogenization rate and the amount of aniline monomer on the performance of microcapsules,the best synthesis conditions of microcapsules were determined:Si O₂ Pickering emulsion was used as emulsifier and the concentration was 1wt.%;Toluene diisocyanate and 1,4-butanediol were used to synthesize polyurethane shell monomer;The homogenization rate was 6000 rpm;The amount of aniline monomer is 0.01 mol.The surface of the microcapsule was dense and rough,and the particle size was 20.01±8.57μm.The average shell thickness is 2.12μm;the chemical structure is ideal;the core material content is 45.1±4.3wt.%.The self-healing and anti-corrosion epoxy resin composite coating was prepared by adding microcapsules into the epoxy resin coating,and its self-healing and anti-corrosion properties were tested,the impedance modulus remains at10⁶Ω·cm² at 0.01 Hz.By comparing the types of microcapsules,the anti-corrosion performance of the composite coating was determined,and it was proved that the core material and shell material had the effect of anti-corrosion at the same time.（2）Tung oil@PU microcapsule,was synthesized by interfacial polymerization in tung oil as core material and polyurethane and polyaniline as wall materials in Si O₂ Pickering emulsion.Tung oil@polyurethane/polyaniline self-healing microcapsules were successfully prepared by in-situ polymerization.The particle size of the microcapsule was 31.1±8.1μm;the core material content is 45.1±4.3wt.%.The self-healing and anti-corrosion epoxy composite coating was prepared,and its self-healing and anti-corrosion properties were tested.The results show that the corrosion resistance of the composite coating with microcapsules is good.After 30 days of immersion,the impedance modulus of the scratch coating with 10wt.%microcapsules is still10⁷Ω·cm² at 0.01Hz.（3）Self-healing microcapsules with controlled release were successfully prepared by using benzotriazole as the core material,polydopamine and polyaniline as the shell material,and the combination of hard template method and in-situ polymerization.The particle size of the microcapsule was 8.3±2.1μm.The thickness of PDA/PANI is about 2μm;the content of core material is about 20wt.%.By comparing the amount and types of microcapsules,the best corrosion resistance of composite epoxy coating was determined.The scratch coating with 1wt.%benzotriazole@polydopamine/polyaniline microcapsules had an impedance modulus of 10⁵Ω·cm² at 0.01Hz after 15 days·It has the best anticorrosion effect.