Structuring of interfacial water on silica surface in cyclohexane studied by surface forces measurement and sum frequency generation vibrational spectroscopy(1)

Masashi Mizukami, Atsushi Kobayashi, Kazue Kurihara

研究成果: Article査読

7 被引用数 (Scopus)

抄録

We investigated interfacial water, formed by adsorption or phase separation (prewetting transition), on a silica surface in water-cyclohexane binary liquids using a combination of colloidal probe atomic force microscopy (AFM) and sum frequency generation (SFG) vibrational spectroscopy. At 33 ± 9 ppm water, the long-range attraction extending to 19.4 ± 2.9 nm appeared, which was caused by the contact of water layers formed on silica surfaces. The attraction range increased with increasing water concentration and reached 97 ± 17 nm at the saturation concentration of water in cyclohexane (C*), indicating that the thickness of the water layer formed on silica was ca. 50 nm. The interfacial energy between the water adsorption layer and bulk solution (γ = 79.3 ± 2.0 mN/m) was estimated from the pull-off force, and was significantly larger than the value for the bulk water/cyclohexane interface (γ = 50.1 mN/m). SFG spectroscopy demonstrated that the interfacial water formed an icelike structure at C*. These results indicated that the interfacial water molecules formed an icelike ordered structure induced by the hydrogen bonding with surface silanol groups, resulting in the free OH groups being more exposed to the bulk solution. On the other hand, the water adsorption layer induced by phase separation at water concentrations above C* was found to be less ordered and its structure at the adsorption layer/bulk interface was almost the same as that of bulk water, although its thickness was almost the same as that formed at C*. To our knowledge, this is the first report of the observation of liquid adsorption layers formed by chemical interaction up to saturation and by the wetting transition above saturation, and their differences in the structure and properties at the molecular level.

本文言語English
ページ(範囲)14284-14290
ページ数7
ジャーナルLangmuir
28
40
DOI
出版ステータスPublished - 2012 10 9

ASJC Scopus subject areas

  • 材料科学(全般)
  • 凝縮系物理学
  • 表面および界面
  • 分光学
  • 電気化学

フィンガープリント

「Structuring of interfacial water on silica surface in cyclohexane studied by surface forces measurement and sum frequency generation vibrational spectroscopy(1)」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル