Preparation And Properties Of Superhydrophobic And Oleophobic Fluorinated Silica Sol

Superhydrophobic surface can effectively reduce contamination.It has wide application in self-cleaning,anti-fog,anti-icing and friction reduction.At present,the methods to prepare superhydrophobic and oleophobic are template,phase separation,vapor deposition,self-assembly and sol-gel,among which sol-gel method has the advantages of simple process,high purity,adjustable shape and size for product.In this work,the modifier heptafluorodecyltriethoxysilane was used to modified a silica sol with a certain size and roughness on the surface that was prepared by sol-gel method by changing the composition and preparation process,after the heptafluorodecylt-riethoxysilane was hydrolyzed and surface grafted to the silica with the heptafluorocarbon groups which make the modified silica have a double hydrophobic function.TEOS,ammonia,ethanol and water are used as precursor,catalyst,dispersing agent and hydrolyzing agent.The uniform size and colloidal stability of nanosilica sol are controlled by reaction temperature and time.The effects of various reaction conditions on the particle size of nanosilica sol were discussed.The optimal reaction conditions were finally determined.The average particle size of the prepared nanosilica sol was 72 nm.The results show that with the increase of reaction temperature,the average particle size of silica sol decreases first and then increases.With the increase of ammonia dosage,water dosage,TEOS dosage and reaction time,the average particle size of silica sol increases within a certain range;The figure shows that nano-silica has a large amount of hydroxyl groups and adsorbed water;the thermogravimetric curve shows that when the temperature reaches 800 ° C,the thermal weight loss rate of nano-silica is 7.9%;XRD spectrum shows that nano-silica is Amorphous matter;SEM electron micrograph shows that nano-silica is a spherical particle with uniform particle size;The contact angle test shows that hydrophilic and lipophilic with contact angle of 46° and 42° for water and hexadecane respectively.A nanosilica sol with heptafluorocarbon groups was prepared by grafting hydrolyzed heptafluorodecyltriethoxysilane to the surface.The modified silica sol is coated on glass slide,non-woven fabric,conductive glass and PET film substrate by shower coating,dip coating and wire bar coating to fabricate superhydrophobic and oleophobic surface.The nanosilica sol with heptafluorocarbon groups and superhydrophobic and oleophobic coating were characterized and analyzed.The results showed that The infrared spectrum shows that the surface of the silica sol modified by heptadecafluorodecyltriethoxysilane is successfully grafted with heptadecafluoroalkyl;the thermogravimetric curve shows that with the modifier heptafluoroquinone The grafting rate also changed with the change of the amount of ethoxysilane;XRD spectrum showed that the heptafluorodecyltriethoxysilane modified fluorinated silica sol did not change the amorphous structure of the nanosilica sol;SEM Electron microscopy and TEM electron micrographs show that the average particle size of the modified fluorinated silica sol increases,showing a solid sphere with organic particles on the surface;The contact angle test results show that the average particle size of the nanosilica sol increases from 72 nm to 265 nm,the water contact angle increases from 46° to 165°,and the hexadecane contact angle is 42.° Increased to 139 °,super hydrophobic and oleophobic performance,and has good weather resistance and heat resistance.