Preparation And Study Of Nano SiO₂/Organosilicon Oligomer Transparent Superhydrophobic Composite Coating

Transparent superhydrophobic coatings have a wide application prospect in automotive glass,architectural glass,solar photovoltaic glass and other fields due to their unique wetting properties,but they cannot be applied in large scale due to poor light transmission,poor wear resistance and high cost.How to improve the light transmittance and wear resistance of transparent superhydrophobic coatings and reduce their production cost have become urgent problems.On the one hand,the surface roughness of superhydrophobic materials and light transmission are contradictory,and the rough structure of the surface will enhance the scattering and reflecting effect of the incident light,thus reducing the light transmission of the material,on the other hand,the poor adhesion and wear resistance limit the application of superhydrophobic materials in practical production.In this study,SiO₂particles were used to construct the surface rough structure,and the effect of SiO₂particles with different particle sizes on the light transmission performance was investigated,and then silicone oligomers were introduced to improve the adhesion and wear resistance of the coating,and the details and results of the study are as follows:（1）According to the stober method,SiO₂particle solution with a minimum average particle size of 45 nm and a maximum particle size of 258 nm were prepared by using ethyl orthosilicate（TEOS）as the raw material and sprayed on glass substrates under different conditions of reaction temperature,TEOS addition and ammonia addition,and then modified by perfluorodecyltrimethoxysilane（PFDT）fluorination to obtain transparent and superhydrophobic coatings.The effect of reaction temperature,addition of TEOS and ammonia on the particle size of SiO₂was firstly investigated,and the results showed that the decrease of reaction temperature,addition of TEOS and increase of ammonia amount would make the particle size of SiO₂larger.The change of TEOS addition had the least effect on the change of SiO₂particle size,while the change of ammonia addition had the greatest effect on the change of SiO₂particle size.Then,the effect of particle size change on the hydrophobicity and light transmission of the coating was investigated on this basis,and the results showed that the increase of particle size would reduce the light transmission performance of the coating,and the larger the particle size,the more significant the effect on the light transmission of the coating,while the increase of particle size would enhance the hydrophobic performance of the coating,and the coating has superhydrophobic performance when the particle size reaches 100 nm or more.（2）A transparent superhydrophobic coating with good adhesion was prepared by using solvated SiO₂particles prepared by the Stober method to construct a surface rough structure and adding alkaline silicone oligomers as bonding agents.The modified SiO₂particle solution was firstly obtained by the Stober method using ethyl orthosilicate（TEOS）as raw material and PFDT as fluorinating agent,and then the modified organosilicone oligomer solution was prepared under alkaline conditions using TEOS withγ-（2,3-epoxypropoxy）propyltrimethoxysilane（KH560）as prepolymer and PFDT as fluorinating agent.The modified SiO₂solution was mixed with the modified alkaline organosilicon oligomer solution in proportion,and finally the mixed solution was sprayed on the glass substrate to obtain a transparent superhydrophobic coating.The effect of the amount of TEOS,KH560 and ammonia in the organosilicon oligomer on the composite coating was investigated.The results surface:when the amounts of ammonia,TEOS and KH560 were 1 m L,6 m L and 0.4 g,respectively,and the ratio of SiO₂solution to the amount of alkaline organosilicon oligomer was 2:1,the contact angle of the coating reached 150°,the light transmission rate was 91%and the adhesion was grade 1.The coating has good self-cleaning properties and can maintain superhydrophobic properties at 300°C.（3）In order to enhance the wear resistance of the coating,Constructs a rough surface on a glass substrate by combining SiO₂composite particles prepared by the Stober method with solid SiO₂particles,acidic organosilicon oligomers prepared with triethoxymethylsilane（MTES）and TEOS as prepolymer as the adhesive,and uses the coupling agent KH540 with fluorosilane The SiO₂composite particle/acidic silicone oligomer composite transparent superhydrophobic coating was prepared on glass substrate by spraying method.The effects of SiO₂composite particles,acidic silicone oligomers and coupling agent KH540 on the composite coating were investigated.The study showed that:when the SiO₂composite particles were composed of two types of particles,solvated SiO₂particles with a particle size of 110 nm and solid SiO₂particles with a particle size of 50 nm;the mass ratio of MTES,TEOS and ethanol in acidic silicone oligomers was 6:3:10;The mass ratio of SiO₂composite particle solution to acidic silicone diluent is 4:1;When the addition amount of coupling agent 3-Aminopropyltrimethoxysilicon（KH540）and fluorosilane PFDT（calculated by the total mass of the mixture,the same below）is both 1%,the composite coating can reach 88%light transmission in the visible wavelength range,the static contact angle can reach155°,and the superhydrophobicity can be maintained after 60 cm of abrasion on 800grit sandpaper,and it has good self-cleaning property and can be applied in practice.It has good self-cleaning property,providing a simple and low-cost solution for the preparation of transparent superhydrophobic coatings.