Molecular orientation and multilayer formation of 1H,1H,8H,8H- perfluorooctane-1,8-diol at the air/water interface

Takanori Takiue, Fumiya Nakamura, Daiki Murakami, Tsubasa Fukuda, Aya Shuto, Hiroki Matsubara, Makoto Aratono

研究成果: ジャーナルへの寄稿学術誌査読

5 被引用数 (Scopus)

抄録

The surface tension of the aqueous solution of lH,lH,8H,8H-perfluorooctane- 1,8-diol (FC8diol) was measured as a function of temperature and concentration under atmospheric pressure. The interfacial density and the entropy and energy of adsorption were evaluated and compared to those obtained for the adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC 10diol) at the hexane solution/water interface. The surface tension curves show a break point corresponding to a phase transition of the adsorbed FC8diol film. The value of mean area per adsorbed molecule A just below the phase transition indicated the formation of a parallel condensed monolayer, and that above the phase transition suggested the spontaneous formation of a multilayer. The multilayer of FC8diol is less compressible and shows a smaller increase in layering with π compared to FC10diol. This is probably because the surface force is repulsive for the hexane/FC/water interface, while it is attractive for the air/FC/water interface. The partial molar entropy change of adsorption is positive in the condensed FC 8diol film, while it is negative in the condensed FC10diol film, which is reasonably explained in terms of the difference in entropy change accompanied by desolvation around the hydrophobic chain. From the viewpoints of the energetic stabilization accompanied by adsorption for the FC8diol system, the contribution from the replacement of air/water contact with air/fluorocarbon and fluorocarbon/water contacts and that from the molecular ordering in the adsorbed film is almost equal in case of the condensed monolayer, while in the multilayer the latter is comparatively larger than the former due to the hydrogen bonding between hydroxyl groups and the dispersion interaction among the ordered hydrophobic chains.

本文言語英語
ページ(範囲)6305-6310
ページ数6
ジャーナルJournal of Physical Chemistry B
113
18
DOI
出版ステータス出版済み - 5月 7 2009

!!!All Science Journal Classification (ASJC) codes

  • 物理化学および理論化学
  • 表面、皮膜および薄膜
  • 材料化学

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