Preparation, properties and formation mechanism of zirconium-Si hybrid high transmittance hydrophobic coating

A two-step synthesis method of a new hybrid coating was discussed. Zirconium silicate hybrid sol was prepared by in-situ hydrolysis polymerization of zirconium acetate (ZrAc) and Octyltrimethoxy silane (OTMS) in alcohol water system. FTIR characterization showed that ZrAc was hydrolyzed and polymerized in situ to form zirconium sol. Octyl trimethoxysilane (OTMS) was hydrolyzed and grafted onto zirconium sol to form octyl coated silicon zirconium hybrid micelles. The co-hydrolysis time of OTMS and ZrAc sol is an important factor affecting the octyl content in ZrAc-OTMS micelles, which affects the hydrophobicity, hardness and light transmittance of the coating. Once appropriately prolonging the co-hydrolysis time, the octyl content in ZrAc-OTMS micelles, hydrophobic angle and light transmittance of the composite coating will increase while the hardness will decrease. Too long co-hydrolysis time will lead to the opposite results. When the co-hydrolysis time is 50 min, the film is drawn on the common glass substrate by one step immersion method. The hydrophobic angle of the coating reaches 132.01°at room temperature. The hardness of pencil is higher than 3 H. The bonding force is Grade 0. The visible light transmittance is 95.30%, and the visible light transmittance of glass matrix is increased by 2.54%. XPS and SEM analysis results showed that the ZrAc-OTMS hybrid coating has a lamellar, micro porous structure with a diameter about 60–200 nm, and low surface energy modified by octyl hydrophobic groups on the micelles, which plays a lotus leaf effect and improves the hydrophobicity of the coating.