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

该研究项目旨在建立一种在等离子体CVD过程中控制防水膜表面形貌和化学键状态的方法，并开发一种在低温下大面积沉积透明、硬质和超防水薄膜的技术。我们利用射频等离子体CVD系统与傅里叶变换红外光谱仪相结合，成功地在80度入射角下通过红外反射吸收光谱（IRRAS）对红外（IR）吸收光谱进行了原位测量（傅立叶变换红外光谱仪）。特别是，选择p偏振IR光可以实现高灵敏度的测量。即使是单层有机硅分子，我们也可以获得红外光谱。通过这种方法，我们建立了一种实时控制薄膜化学键状态的沉积技术。人们认为，由于疏水性Si-OH基团的形成，用氧气的混合物无法合成超疏水薄膜。然而，我们明确指出，在相对较高的总压（150-200 Pa）和氧气混合物下，可以实现超防水性。从该结果可以预见，形成具有硬度的防水膜。尽管这些薄膜含有 Si-OH 官能团，但仍具有超强防水性。其原因尚未阐明，可以作为一个有趣的研究对象。通过环境扫描电子显微镜观察拒水性。即使对于μm大小的水滴，接触角也超过150度。

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.