Development of Transparent Super Water-repellent Films by Composing Surface Fine Structure

本研究旨在建立一种在等离子体CVD过程中同时控制防水薄膜表面形貌和化学键状态的方法，并开发一种大面积低温沉积透明、坚硬和超防水薄膜的技术。利用射频等离子体CVD系统结合傅里叶变换红外光谱仪(FTIR)，成功地在80°入射角下用红外反射吸收光谱(IRRAS)原位测量了红外吸收光谱。特别是选择p偏振红外光，使测量具有较高的灵敏度。我们甚至可以获得有机硅分子的单分子膜的红外光谱。通过这种方法，我们建立了一种沉积技术来实时控制薄膜的化学键状态，假设由于形成疏水的Si-OH基团，在氧气和气体的混合物中不能合成超级憎水薄膜。然而，我们清楚地表明，在相对较高的总压下，在150-200帕的范围内，与氧气的混合物可以实现超级憎水。从这一结果可以预期，形成具有硬度的拒水膜。虽然膜中含有Si-OH官能团，但具有超强的拒水性能。其原因尚未阐明，可能是一个有趣的研究对象。通过环境扫描电子显微镜观察了其拒水性能。即使是μm大小的水滴，接触角也在150度以上。

This research project aimed at an establishment of a method to control both the surface morphology and the chemical bonding states of the water-repellent films in plasma CVD processes and at a development of a technique ton deposit transparent, hard and super water-repellent films at low temperature over wide area.We succeeded in in-situ measurement of infrared (IR) absorption spectra by infrared reflection absorption spectroscopy (IRRAS) at an incident angle of 80 degree using an rf plasma CVD system combined with a Fourier-transform infrared spectrometer (FTIR). Especially, selecting p-polarized IR light lead to measurement at a high sensitivity. We could obtain IR spectra even for a monolayer of organsilicon molecules. By means of this method, we established a deposition technique to control the chemical bonding states of the films in real time.It has been supposed that super water-repellent films cannot be synthesized with mixture of an oxygen has gas because of formation of hydrophobic Si-OH groups. We made clear, however, that super water repellency can be realized at relatively higher total pressure, in the range of 150-200 Pa, with the mixture of oxygen. From this result, it can be expected that the formation of water-repellent films with hardness. The films have super water-repellency although they include Si-OH functional groups. The reason has not been elucidated and can be an interesting research object.The water repellency was observed by means of environmental scanning electron microscope. The contact angle was over 150 degree even for the water drops in μm size.