Preparation Of Waterborne Superhydrophobic Coats And Studying Their Self-cleaning Property

As the economy developing,we are surrounded by more and more buildings.Now,in addition to their functions,their appearance is attracted more and more attentions.However,the various pollutants of the nature are making the original brand-new building to be dirty,destroying the original appearance of buildings.Then,the city will lose its beauty and vitality.It will spend a lot of manpower and resources to remove these stains.Therefore,developing a high-performance self-cleaning coating can be a good solution to solve this problem.In this study,we firstly prepared fluoride silicone sol by mixing heptadecafluorodecyl silane?FAS-17?and?-aminopropyl triethoxysilane?KH-550?.Then the nano SiO₂ was dispersed into such sol and further together mixed with two types of waterborne coat?epoxy resin and silicone acrylic emulsion?.By optimizing formula,we successfully obtained two kinds of waterborne superhydrophobic coat.To water-based epoxy resin emulsion,the formula is as follwoing:1.5 g nano SiO₂,2.0 g waterborne epoxy resin?EP-51?,2.0 g Epoxy curing agent?HGF?,0.3 mL FAS-17,0.6 mL KH-550.The resulted coat showed the excellent superhydrophobic properties:contact angle up to 156.7°and the sliding angle low to 6.2°.To silicone acrylic emulsion,the formula is as following:2.0 g nano SiO₂,2.5 g acrylic emulsion,0.3 mL FAS-17,0.6mL KH-550.The coat also showed excellent superhydrophobic properties:contact angle tu to 156.8°and the sliding angle low to 7.5°.Finally,we measured the fouling resistance property of the superhydrophobic coat.The test includes the resistance to dust,the contact angle of various types of liquid,water immersion and outdoor test for a long time.Experiments showed that the superhydrophobic coat have a good self-cleaning ability to the dust,e.g,the dusts can be easily driven away by raining or water.The outdoor condition has a little effect on the self-cleaning property.However,the superhydrophobic coat showed poor resistance to water immersion.After immersing in water for certain time,the superhydrophobic surfaces were wetted.The mechanism may be that the polar group below the surface turns to outmost surface,which makes the wetting state of water changes to Wenzel state from Cassie state.How to increase the fluorine content while remain low price may be the direction in developing superhydrophobic and self-cleaning coat.