| Superhydrophobic coating has unique functions such as hydrophobic,anti-fog and anti-icing,and can realize surface self-cleaning,fluid drag reduction and oil-water separation,which has attracted attention and research in many fields.The low surface energy and the microscopic graded roughness determine the hydrophobicity of the surface.In recent years,the preparation of superhydrophobic materials often uses expensive fluorine compounds as low surface energy materials,and the microscopic roughness of the surface is poor in durability and complicated in preparation,thus inhibiting the development and application of superhydrophobic materials.In this paper,methyl vinyl silicone resin(MVSR),which can realize double cross-linking curing(ultraviolet curing and condensation curing),had been synthesized as low surface energy material,vinyltriethoxysilane(VTEO)modified nano-SiO2(VTEO-SiO2)particles were used to construct surface roughness,and a new method for preparing superhydrophobic materials was studied.Since MVSR is prone to oxygen inhibition in the surface of UV curing process,the residual-Si-CH=CH2 group in the oxygen barrier layer acts as an active site for reaction with VTEO-SiO2 By further UV curing,the chemical bonding of VTEO-SiO2 and MVSR substrate is skillfully combined,which increases the mechanical properties of the superhydrophobic coating.Since the silicone resin has excellent water repellency and chemical stability,the use of a silicone resin instead of a fluoride can greatly reduce the preparation cost of the superhydrophobic material.In this paper,MVSR prepolymer was synthesized by acid-catalyzed hydrolysis condensation reaction of siloxane monomer.The effects of reaction conditions oin the crosslink density and yield of MVSR and the effect of different R/Si ratios in MVSR on WCA were investigated.After the MVSR is cured,the coating WCA is 99 to 104°.In order to further improve the hydrophobicity of the coating,perfluorodecyltriethoxysilane(PFDTES)was added during the synthesis of MVSR to synthesize fluorine-containing methyl vinyl silicone resin(FMVSR).Aftercuring,the WCA can be improved to 108°.Conventional silicone coating curing generally uses condensation curing,which is slower to cure.In order to increase the curing speed of the silicone resin,a curing method using ultraviolet light(UV)curing is employed.By introducing a photosensitive group(vinyl group)into the silicone resin structure,it is possible to achieve rapid curing molding of the silicone resin for 2 minutes.By adjusting the content of vinyl in MVSR,it is found that UV curing can be achieved when the vinyl content of MVSR is not less than 14wt%,and the coating performance is excellent in the range of 14-16wt%without cracking.In order to enhance the mechanical properties of the silicone resin,condensation curing can be further carried out to achieve MVSR double cross-linking curing.In order to improve the hydrophobic properties of the coating surface,the hydrophobic coating was first prepared by mechanical mixing of MVSR and VTEO-SiO2 by double crosslinking curing.When adding 5 wt%of VTEO-SiO2,the WCA was at most 137°.It was found by SEM that VTEO-SiO2 was embedded in the silicone layer,which affected the microstructure of the surface and did not achieve superhydrophobic surface.In order to further improve the hydrophobicity of the coating,the VTEO-SiO2 powder was used to spray the UV-cured MVSR oxygen barrier layer.Due to the agglomeration of the SiO2 powder and uneven distribution on the surface,the WCA was at most 141°.In order to improve the dispersion of VTEO-SiO2 particles in the MVSR oxygen barrier layer,an oxygen solution layer was used to dip the VTEO-SiO2 ethanol solution.When the mass fraction was 1.2wt%VTEO-SiO2 modified surface,the coating WCA was at most 154° and the surface is superhydrophobic.The superhydrophobic coating has self-cleaning ability and has small adhesion,and the light transmittance is above 66.03%in the visible light range,and is resistant to acid and water. |
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