TEOS/OTMS超疏水涂层的制备及形成机制

Preparation and Formation Mechanism of TEOS/OTMS Superhydrophobic Coating

以正硅酸乙酯(TEOS)和正辛基三甲氧基硅烷(OTMS)为原料,采用溶胶-凝胶法制备了TEOS-OTMS溶胶,分别在光滑玻璃基体、刻蚀玻璃基体上,通过一步浸渍提拉法制备了疏水涂层,研究了水解时间对涂层疏水性能和硬度的影响,提出了TEOS-OTMS溶胶与疏水涂层形成机制。结果表明:TEOS-OTMS原位水解-聚合可以制备以SiO颗粒为胶核,辛基硅烷包覆的胶体粒子,在玻璃基体形成辛基链修饰的低表面疏水膜层,当TEOS预水解聚合4 h, TEOS-OTMS共水解聚合20 min时,涂层疏水角达到(124.01±2.00)°,铅笔硬度达到6 H。利用扫描电子显微镜对微观结构进行分析,玻璃基体通过刻蚀形成间距6.36 nm、平均大小16.75 nm的微观凸起,使TEOS与OTMS的缠结、聚集增强,涂层形成了150~200 nm的孔隙,这种“微观粗糙”是形成超疏水涂层的关键,TEOS-OTMS涂层疏水角达到(160.08±2.00)°。

TEOS-OTMS sols were prepared by sol-gel method using tetraethyl orthosilicate(TEOS) and octyl trimethoxysilane(OTMS) as raw materials. Hydrophobic coatings were prepared on a smooth glass substrate and an etched glass substrate by one-step immersion method. The effects of hydrolysis time on the hydrophobicity and hardness of the coating were studied. The formation mechanisms of TEOS-OTMS sol and hydrophobic coating were proposed. Results showed that colloidal particles with SiOparticles as the glue core and octylsilane as the cover could be prepared through TEOS-OTMS in-situ hydrolysis polymerization. And a low surface hydrophobic film modified by an octyl chain could take shape on the glass substrate. When TEOS was treated with pre-hydrolysis polymerization for 4 h and the TEOS-OTMS was treated with co-hydrolysis polymerization for 20 min, the hydrophobic angle of the coating reached(124.01±2.00)° and the pencil hardness reached 6 H. The result of an microstructure analysis by scanning electron microscope showed that the glass substrate was etched to form micro protrusions with a spacing of 6.36 nm and an average size of 16.75 nm, which enhanced the entanglement and aggregation of TEOS and OTMS, and pores of 150~200 nm formed in the coating. This “micro roughness” was the key to the formation of superhydrophobic coating, and the hydrophobic angle of the TEOS-OTMS coating reached(160.08±2.00)°.