Preparation And Properties Of Fluoride-Free Superhydrophobic Methylated Silica

Superhydrophobic materials have great potential application in moisture resistance,oil-water separation,anti-fingerprint,self-cleaning and anti-corrosion.Etching,template,deposition are three common methods to prepare superhydrophobic materials.However,these methods have shortcomings of complex preparation process,expensive experimental reagent and serious environmental pollution.In this work,monodisperse SiO₂ sol was prepared by sol-gel method,then the superhydrophobic SiO₂ with the methyl groups on the surface was prepared by the surface modification of MTMS to monodisperse SiO₂.Superhydrophobic SiO₂ sol was successfully coated on the surfaces of glass,dust-free cloth and cotton.The application of superhydrophobic coatings for self-cleaning and oil-water separation was also studied.In addition,an organic-inorganic complex superhydrophobic coating was prepared by using epoxy resin as matrix and superhydrophobic SiO₂ sol as filler.The performance of superhydrophobic coating in anticorrosion was studied.Monodisperse SiO₂ was prepared by sol-gel method using ethanol as solvent,TMOS and water as reactant and ammonia as catalyst.The effects of the amount of solvent and ammonia,the reaction temperature on the particle size and distribution of SiO₂ were studied.FTIR spectroscopies indicated that the surfaces of the SiO₂ contained a large amount of hydroxyl groups and adsorbed water.XRD record showed that the SiO₂ was amorphous and SEM photos indicated the shape and the distribution of the particle size was spherical and uniform.The particle size was 110 nm.The hydrophilic SiO₂ coating can be obtained by coating SiO₂ sol on the surface of transparent PET film.The SiO₂ coating had antireflective effect,the maximum transmittance was 92%,and the contact angle of the coating was 7.6°.The SiO₂ with the methyl groups on the surface was prepared by core-shell method with MTMS as modifier.The effect of the amount of MTMS on the wettability of the SiO₂coating was studied.The results showed that when the mass ratio of MTMS to TMOS was0.7,the contact angle of the coating was 164°.Superhydrophobic surfaces on glass,dust-free cloth and cotton had been successfully constructed by spraying and dipping coating of the prepared superhydrophobic SiO₂ sol.Superhydrophobic glass and cotton showed excellent self-cleaning performance.Superhydrophobic dust-free cloth had great potential application in the field of oil-water separation.The separation efficiency of different oil-water mixtures was higher than 96%which can be reused for many times.The EP/M-SiO₂ hybrid coating was prepared with epoxy resin as matrix and the methylated SiO₂ sol(M-SiO₂)as filler.The surface of the tinplate was coated with anti-corrosion EP/M-SiO₂ hybrid coating to evaluate the anti-corrosion of EP/M-SiO₂.The effects of the amount of M-SiO₂ on the wettability and corrosion resistance of the EP/M-SiO₂coating were investigated.The results showed that when the amount of M-SiO₂ was50%,the contact angle of the coating reached 153°,the hardness was 2 H,and the adhesion was 1.When the surface of the tinplate was coated with EP/M-SiO₂ superhydrophobic coating,the corrosion current density of the tinplate was only 0.76?A/cm²,and the corrosion inhibition efficiency was 98.9%;It was placed in 5wt%HCl and Na OH solution for 24 hours,there was no trace of corrosion on the surface of the iron piece.All these tests indicate that the coating had excellent anti-corrosion effect.