Preparation Of Slow-release Self-healing Microspheres And Its Application In Coatings

Corrosion prevention of metals is a very important issue in daily life and industrial production in today’s society.Anti-corrosion coatings are the most effective and simple methods.However,it is difficult for ordinary coatings to protect metals when they are damaged continuously.In order to protect metals against corrosion for a longer period of time,people have begun to study anti-corrosive coatings with self-repairing functions.In the anti-corrosion coating with self-healing function,the research and development of self-healing capsule materials has become one of the hot research directions of materials workers.To this end,a sol-gel method combined with electric double layer coating technology was used to prepare a nano-self-repairing silica microsphere capsule loaded with corrosion inhibitor BTA,and explore its slow-release effect.Hollow silica microspheres prepared with PS microspheres as hard templates are used as the carrier of corrosion inhibitors.We adjust the preparation process parameters of PS microspheres such as particle size,surfactant,precursor type,etc.,and optimize the preparation under suitable vacuum impregnation Slow-release self-repairing hollow silica microspheres with controlled pore size and high BTA loaded.Double-layer coating technology is used to modify the polyelectrolyte double-layer on the surface of BTA-loaded hollow silica microspheres,and a PEI/PSS double-layer coating type with rapid response release function under alkaline conditions is constructed.The specific research results are as follows:1)The polystyrene（PS）microspheres are prepared by the emulsion polymerization method,adjusting the process parameters such as the volume ratio of alcohol to water in the reaction system.When the volume ratio of alcohol to water is 1:0,4:1,1:1 and 0:1,the average particle size of the prepared PS microspheres is about 1700 nm,670 nm,370 nm and 270 nm,respectively.2)Using PS microspheres with different pore sizes as hard templates,hollow mesoporous silica microspheres were prepared by sol-gel method.The effects of ammonia water dosage,surfactant CTAB dosage and silicon source TEOS dosage on the microstructure and specific surface area of hollow mesoporous silica microspheres were investigated.The best preparation conditions for hollow mesoporous silica microspheres are:using 5 g PS-4 as a hard template,in250 mL ethanol and 25 mL water solvent system,1 g CTAB amount,ammonia water 12.5 mL,TEOS dosage is 10 g.3)Using double-layer coating technology to carry out corrosion inhibitor loading and double-layer coating treatment on hollow silica microspheres,preparing PEI/PSS double-layer coating type with BTA loading of about 45 wt.%self-healing microspheres.It can be seen from the slow-release curve that the BTA release rate of the double-layer coated self-healing microspheres under alkaline conditions is about 14.0μg mL^-1 h^-1 in the initial 1 hour,which is double the neutral.4)Add self-repairing microspheres coated with electric double layer to epoxy coating to prepare self-repairing epoxy coating.The EIS results show that the resistance of the coating added with self-healing microspheres is about an order of magnitude higher and has better corrosion resistance.