Venkateswara Rao A, Latthe Sanjay S, Nadargi Digambar Y, Hirashima H, Ganesan V
Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra, India.
J Colloid Interface Sci. 2009 Apr 15;332(2):484-90. doi: 10.1016/j.jcis.2009.01.012. Epub 2009 Jan 14.
Superhydrophobic surfaces with water contact angle higher than 150 degrees generated a lot of interest both in academia and in industry because of the self-cleaning properties. Optically transparent superhydrophobic silica films were synthesized at room temperature (27 degrees C) using sol-gel process by a simple dip coating technique. The molar ratio of MTMS:MeOH:H(2)O (5 M NH(4)OH) was kept constant at 1:10.56:4.16, respectively. Emphasis is given to the effect of the surface modifying agents on the hydrophobic behavior of the films. Methyl groups were introduced in the silica film by post-synthesis grafting from two solutions using trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ) silylating agents in hexane solvent, individually. The percentage of silylating agents and silylation period was varied from 2.5 to 7.5% and 1 to 3 h, respectively. The TMCS modified films exhibited a very high water contact angle (166+/-2 degrees) in comparison to the HMDZ (138+/-2 degrees) modified films, indicating the water repellent behavior of the surface. When the TMCS and HMDZ modified films were heated at temperatures higher than 350 degrees C and 335 degrees C, respectively, the films became superhydrophilic; the contact angle for water on the films was smaller than 5 degrees. Further, the humidity study was carried out at a relative humidity of 85% at 30 degrees C temperature over 30 days. The films have been characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), % optical transmission, humidity tests and contact angle (CA) measurements.
水接触角高于150度的超疏水表面因其自清洁特性在学术界和工业界都引起了广泛关注。采用溶胶-凝胶法，通过简单的浸涂技术在室温（27摄氏度）下合成了光学透明的超疏水二氧化硅薄膜。MTMS:MeOH:H₂O（5M NH₄OH）的摩尔比分别保持在1:10.56:4.16不变。重点研究了表面改性剂对薄膜疏水行为的影响。通过在己烷溶剂中分别使用三甲基氯硅烷（TMCS）和六甲基二硅氮烷（HMDZ）硅烷化剂从两种溶液进行后合成接枝，将甲基引入二氧化硅薄膜中。硅烷化剂的百分比和硅烷化时间分别在2.5%至7.5%和1至3小时之间变化。与HMDZ（138±2度）改性薄膜相比，TMCS改性薄膜表现出非常高的水接触角（166±2度），表明表面具有疏水行为。当TMCS和HMDZ改性薄膜分别在高于350摄氏度和335摄氏度的温度下加热时，薄膜变得超亲水；薄膜上的水接触角小于5度。此外，在30摄氏度温度、85%相对湿度下进行了30天的湿度研究。通过扫描电子显微镜（SEM）、原子力显微镜（AFM）、傅里叶变换红外光谱（FT-IR）、%光学透过率、湿度测试和接触角（CA）测量对薄膜进行了表征。
