Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University, Seta, Otsu 520-2194, Japan.
Langmuir. 2013 Jun 25;29(25):8164-9. doi: 10.1021/la4014834. Epub 2013 Jun 4.
We identified the mechanism of the formation of needle-shaped microcrystals on which the contact angle of a water droplet exceeds 170° [Nishikawa, N. et al. Langmuir, 2012, 28, 17817-17824]. The standing needle-shaped crystal of the closed-ring isomer of a diarylethene 3c grew at a much lower temperature than the eutectic temperature by irradiation of UV light on the thin films of the open-ring isomer 3o, due to the epitaxial growth of the 013 plane of 3c over the 110 plane of the crystal lattice of 3o in the subphase. Therefore, the new crystal-growth mechanism triggered by the photoisomerization does not require special inorganic single-crystal substrates and may be called self-epitaxial crystal growth. The needle-shaped crystals appeared well-ordered and stood inclined at an angle of about 60° to the surface. Consequently, the photo-induced rough surface shows not only the superhydrophobic lotus effect, but also the antireflection moth-eye effect, and these effects were switchable by alternate irradiation with UV and visible light.
我们确定了形成水滴接触角超过 170°的针状微晶的机制[Nishikawa, N. 等人，Langmuir，2012，28，17817-17824]。在亚相中，由于 3c 的 013 平面在 3o 晶格的 110 平面上外延生长，因此，通过对开环异构体 3o 的薄膜进行紫外光照射，二芳基乙烯 3c 的闭环异构体的立起针状晶体在比共晶温度低得多的温度下生长。因此，由光致异构化引发的新的晶体生长机制不需要特殊的无机单晶衬底，可称为自外延晶体生长。针状晶体排列整齐，倾斜约 60°立在表面上。因此，光诱导的粗糙表面不仅显示出超疏水的莲花效应，还显示出防反射的蛾眼效应，这些效应可以通过交替照射紫外光和可见光来切换。
