Preparation And Properties Of Transparent Superhydrophobic Coating Based On Nano-silica

Transparent superhydrophobic coatings have good application potential in fields of optical devices,solar panels,automobile windshields,and building glass exterior walls,because of its high optical transmittance and little effect on the appearance of the substrate.However,the problem of transparent superhydrophobic coatings is that the preparation process is complicated.The rough structure is relatively fragile and the durability of the coating is poor.It is difficult to get superhydrophobic coatings with high transparency.Therefore,exploring transparent superhydrophobic coating with a simple preparation method and good durability has very important research significance.In this paper,hybrid silica sol and organosilicon oligomer were prepared by sol-gel process.The transparent superhydrophobic composite coatings were obtained via incorporating the hybrid silica sol and organosilicon oligomer.The research contents of this thesis are as follows:Firstly,hybrid silica sol was prepared by sol-gel process using fumed silica,tetraethoxysilane(TEOS)and hexamethyl-disilazane(HDMS)as raw materials.It was coated on the surface of the glass slides to obtain transparent superhydrophobic films.The effect of sol-gel process,fumed silica and HDMS on the hydrophobic property of hybrid silica sol coatings was investigated.The results show that the excellent performance of hybrid silica sol coatings could be obtained with the water contact angel(CA)of 166° and the sliding angel(SA)of less than 3°.With the increase of fumed silica,the surface roughness rises and the hydrophobicity improves.The dosage of HMDS has an important influence on the hydrophobic of the coatings.The optical transmittance of the hybrid silica sol coating was as high as 89.6%at 550 nm.Secondly,the transparent superhydrophobic composite coatings were obtained via incorporating the hybrid silica sol and organosilicon oligomer which is synthesized with 2,3-Epoxypropoxy propyltrimethoxysilicane(KH560)and methyltriethoxysilane(MTES).The effects of the preparation process of organosilicon oligomer on the performance of the composite coating were studied,and the dosage of organosilicon oligomer on the properties of composite coating was investigated.The micro-morphology of the composite coating was characterized by SEM.The results show that with the increase of the dosage of KH560,the durability of the composite coating increases.But too much KH560 will reduce the hydrophobic properties of the composite coating.Increasing the dosage of silicone oligomer can improve the stability of the composite coating,but it will lead to a decrease in the transmittance of the composite coating.When the dosage of silicone oligomer is 10%of the mass fraction of hybrid silica sol,the CA of the prepared superhydrophobic composite coating was 165°,and optical transmittance at 550 nm was 85.4%.Finally,the mercapto group was introduced into the hybrid silica sol and the photosensitive organosilicon oligomer was synthesized with 3-(Trimethoxysilyl)propyl methacrylate(KH570)and MTES.The UV-curable coating is made up of mercapto-modified hybrid silica sol,photosensitive organosilicon oligomer,trimethylolpropane triacrylate(TMPTA)and photoinitiator 1173.The effect of hybrid silica sol prepared by different dosage of KH590 on the performance of the composite coating was studied,and the effects of dosage of photosensitive organosilicon oligomer and UV-curing process were investigated.The micro-morphology of the composite coating was characterized.The results show that KH590 can improve the UV-curing process and enhance the stability of the composite coating.Increasing the dosage of KH570 can also help to improve the UV-curing process.The increased dosage of TMPTA will improve the stability of the composite coating,but will reduce the hydrophobicity of the composite coating.When the molar ratio of KH570 to MTES is 0.75:1,the amount of double bond-containing silicone oligomer is 6%of the mass fraction of the sulfhydryl-modified hybrid silica sol,the dosage of TMPTA is 0.050 g and photoinitiator 1173 is 0.010 g,the CA of the composite coating is 165°,the contact angle after ultrasound is 142°,and the optical transmittance at 550 nm reaches 82.8%.