title: Photoinduced self-epitaxial crystal growth of a diarylethene derivative with antireflection moth-eye and superhydrophobic lotus effects.
abstract: 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.
authors.affiliation: Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University, Seta, Otsu 520-2194, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Nishikawa
authors.forename: Shingo
authors.initials: S
authors.lastname: Sakiyama
authors.forename: Seiji
authors.initials: S
authors.lastname: Yamazoe
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kojima
authors.forename: Ei-ichiro
authors.initials: E
authors.lastname: Nishihara
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tsujioka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mayama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yokojima
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Kingo
authors.initials: K
authors.lastname: Uchida
mesh_terms: D003460:Crystallization; D005030:Ethylenes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D010777:Photochemistry / Q000379:methods*; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D005030:Ethylenes; C036216:ethylene