Preparation And Corrosion Resistance Mechanism Of Glycerine Microcapsules Coated With Silane-Epoxy Coating

Aiming at the service life of organic coatings on metal materials,based on the research basis of self-healing coatings,self-healing coating system with DAG@PSF microcapsules silane-epoxy were designed and constructed.And the corrosion resistance of metal surface was improved and self-healing function was realized by adjusting the properties of 1,2,3-glycerol（DAG）-polysulfone（PSF）microcapsules.DAG@PSF microcapsules were prepared by solvent evaporation method.The morphology,structure,thermal stability,corrosion resistance and other related properties of the microcapsules were studied by scanning electron microscopy（SEM）,infrared thermogravimetry（TGA）and other means.The properties of DAG@PSF microcapsules were improved by changing the preparation parameters of microcapsules.Meanwhile,the silane-epoxy self-healing coatings with different carrying capacities of DAG@PSF microcapsules were prepared by brush coating method.The influence of different carrying capacity of microcapsule on corrosion resistance of coating was investigated.The corrosion resistance of the silane-epoxy self-healing coating with DAG@PSF microcapsules was compared with that of epoxy coating and silane-epoxy blend coating,and the electrochemical behavior of three organic coatings in corrosive media was explored.At the same time,the corrosion behavior and self-healing mechanism of the silane-epoxy self-healing coating loaded with DAG@PSF microcapsules were explored.The main research contents and conclusions are summarized as follows:（1）PFS polymer microcapsules loaded with DAG were prepared by solvent evaporation method,and the best preparation technology was found by adjusting the process parameters.The microstructure,chemical structure and thermal stability of DAG@PSF microcapsules were analyzed by scanning electron microscopy（SEM）,optical microscopy（OM）,Fourier transform infrared spectrometer（FTIR）and thermogravimetric analyzer（TGA）.The results showed that the encapsulation performance of microcapsules was higher when the emulsifier dosage was 1 m L,the emulsification revolution was 1200 rpm and the core material ratio was 2:1.DAG@PSF microcapsule is a spherical shell with uniform and dense internal cavity,with a diameter of about 150μm and a wall thickness of about 16μm.Chemical structure analysis and thermal stability analysis showed that DAG was successfully coated into PSF,and the maximum coating amount of DAG was 12.5%.（2）Based on the principle of silane hydrolysis,the silane monomer is directly doped into the epoxy resin coating to prepare the silane epoxy blend coating to reduce the water content of the coating.Electrochemical impedance spectroscopy（EIS）was used to investigate the water absorption performance of the coating and the corrosion resistance of the silane epoxy blend coating.The results showed that the impedance modulus of silane monomer doped with epoxy resin reaches 1.1×10⁷.The saturated water absorption of the coating decreased first and then increased with the increase of silane doping amount.At the same time,it was found that the absorption peak intensity of 1100cm^-1in the infrared spectrum was slightly enhanced after the silan-doped coating was soaked,which was due to the formation of the reticular structure Si-O-Si.It is proved that the silane doping successfully reduces the water content of the coating and improves the corrosion resistance of the silane-epoxy blend coating.（3）The silane-epoxy self-healing coating with DAG@PSF microcapsules was prepared by doping DAG@PSF microcapsules.Scanning electron microscopy（SEM）,electrochemical impedance detection（EIS）and scratch test systems were used to compare the performance of DAG@PSF microencapsulated silan-epoxy self-healing coating with epoxy resin coating/epoxy resin self-healing coating.The electrochemical corrosion behavior and self-healing behavior of the three coatings before and after immersing for seven days were analyzed.The results show that the coating has excellent corrosion resistance with the addition of DAG@PSF microcapsules and silane,and the impedance modulus can still reach 1.2×10⁶Ω/cm²after seven days of immersion.The coating still has good corrosion resistance,and the corrosion rate of metal is reduced.At the same time,the self-healing mechanism of DAG@PSF microcapsule silane-epoxy self-healing coating after damage was proved and analyzed by scratch experiment.