Preparation And Properties Of Polydimethylsiloxane/Micro-nano Composite Super Hydrophobic Coatings

There are many strange and incredible surface phenomenon in nature. Lotus leaf has attracted scholars’extensive attention because of its funky surface performance. Surface Kind of lotus leaf can bring stain adhering to the surface away under the action of rain and keep clean due to the high static contact Angle and low rolling Angle. Water-based super hydrophobic self-cleaning coatings inspired and prepared by lotus leaf has been wildly used in real life and production. Sorts of methods can be used to prepare self-cleaning coatings. But these methods exist the problem of high preparation cost, not easy to operate or difficult to be prepared widely. To explore a simple and convenient preparation method for the practical application of water-based self-cleaning coating is of great significance.In this paper, we choose the mixture emulsion of organic silicon with low surface energy and conventional acrylic as film forming material. Hydrophilic silica nanoparticles or micron particles of calcium carbonate is used to create rough structure. Water-based super hydrophobic self-cleaning coatings can be successfully made through appropriate modification. The concrete research content is summarized as follows:(1) Polydimethylsiloxane type emulsion of low surface energy was successfully synthesized by emulsion polymerization with polydimethylsiloxane, butyl methacrylate as reaction monomer,2,2’-Azobisisobutyronitrile as initiating agent. Then we examine and text the following basic properties:the average particle size of the hydration (Dh), the product’s chemical constitution and structure, wettability and so on. At the same time, we discuss the changes of the coating’s water contact angle after mixed with the traditional acrylic emulsion. Research shows that the wettability of pure polydimethylsiloxane emulsion is close to that of the mixed emulsion of pure polydimethylsiloxane and acrylic which helps the practical application of this kind of waterborne emulsion for its economic benefit.(2) Hydrophilic silica nanoparticles and micron particles of calcium carbonate are respectively decentralized to a certain Dh under the action of pure water. Different percentage of hydrophilic silica nanoparticles, micron particles of calcium carbonate and mixing of hydrophilic silica and calcium carbonate particles are added to the hybrid emulsion of PDMS2250 and acrylic acid. The film’s forming performance under different ratios is discussed. The addition of suitable amount of hydrophilic silica nanoparticles or micron particles of calcium carbonate particles can be effective in getting the right and ideal rough structure to prepare super hydrophobic self-cleaning coatings.(3) The further research for the hybrid system of PDMS2250/comex/silica has been carried on. The further research finds that as part of the hydrophilic silica is exposed on the surface, not completely covered by PDMS2250 emulsion, the coatings’ rolling contact angle is still a little larger. The coatings don’t own the property of self-cleaning. By further chemical vapor deposition treatment of 1H,1H,2H,2H-perfluorodecyltrichlorosilane, the surface is covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane. These coatings exhibited self-cleaning properties with super hydrophobicity.