Preparation Of Modified Nano-silica Sol And Its Application In Transparent Superhydrophobic Coatings

According to the principle of bionics,people construct various super-hydrophobic surfaces by constructing a rough surface of a layered micro-nano structure or adjusting the chemical composition to reduce the surface energy.Surfaces with a water contact angle greater than 150° are called superhydrophobic surfaces.The transparent super-hydrophobic surface with high transparency is one of the special super-hydrophobic surfaces.It can be used not only for car rearview mirrors,aircraft windshields and architectural curtain wall glass,but also for solar panels.Due to its huge application potential,transparent superhydrophobic coatings have become a research hotspot in recent years.In this study,we tried to achieve a suitable balance between surface roughness and optical transmittance,and explored how to prepare transparent superhydrophobic coatings on glass substrates.Nano silica sol is a kind of nano particles with a large number of hydroxyl groups on the surface.It has the characteristics of low preparation cost and controllable particle size and distribution.When the particle size of the silica particles is smaller than or close to the wavelength of visible light,the coating layer exhibits good visible light permeability.Due to the presence of a large number of hydroxyl groups on the surface of the silica,it can be modified by alkylation to obtain monodisperse modified nano silica sol with small particle size,which can be used to prepare transparent super-hydrophobic coatings.Therefore,the main research contents of this article are as follows:(1)Using ethyl orthosilicate as the hydrolysis precursor,nano-silica sols with different particle sizes were prepared by the sol-gel method.Combined with spin coating technology and ultraviolet light curing technology,micro-silicon sols were successfully prepared on glass substrates.Nano-silica coating with nano-rough three-dimensional structure.In view of the existence of-OH on the surface and the large porosity,the hydrophobic properties and transparency are not good enough,so the performance of the product has been further improved,so that the visible light transmittance reaches 90%,and the contact angle of water reaches 145°,The rolling contact angle is less than 10°.(2)On the basis of small-diameter monodisperse nano-silica sol,different types of silane are used as modifiers,and the nano-silica sol modified by different modifiers is prepared by insitu modification method,and then combined with spin coating Technology and ultraviolet curing technology successfully prepared different modified nano-silica coatings on glass substrates.Among them,because the modifier 1,1,3,3-tetramethyl-1,3-divinyldisilazane has the characteristics of other modifiers,its modified nano-silica coating also has a micro-nano rough three-dimensional structure,low surface energy And the advantages of less porosity,so that the coating has both good hydrophobicity and excellent transparency.(3)Characterized by using Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),thermogravimetric analyzer(TGA),ultraviolet-visible(UV-vis)light spectrophotometer,laser particle size analyzer,contact angle meter,etc.The various structures and properties of the nano-silica coating are analyzed,and the test results are systematically analyzed.The visible light transmittance of the nano-silica coating modified by 1,1,3,3-tetramethyl-1,3-divinyldisilazane can reach 90% The contact angle of water can reach 145°,and the rolling contact angle is less than 10°,which is significantly improved compared to the unmodified nano-silica coating.