Force measurements between semifluorinated thiolate self-assembled monolayers: Long-range hydrophobic interactions and surface charge

T. Ederth, K. Tamada, P. M. Claesson, R. Valiokas, R. Colorado, M. Graupe, O. E. Shmakova, T. R. Lee

研究成果: Contribution to journalArticle査読

16 被引用数 (Scopus)

抄録

Long-range interactions between self-assembled monolayers (SAMs) of semifluorinated alkanethiols have been studied by direct force measurements in water and aqueous NaCl solutions. SAMs prepared from three different thiols, with identical fluorinated head groups but varying hydrocarbon spacer lengths, were investigated: CF3(CF2)9(CH2)xSH, where x = 2, 11, or 17. Force measurements show that the interactions in water and electrolyte solutions are composed of both double-layer interactions emerging from what appears to be charges adsorbed onto the surfaces and long-range "hydrophobic" attractions, in excess of the expected van der Waals forces. The three investigated thiols produce similar results in force measurements, though the contact angles with water are slightly different. The "hydrophobic" attraction has the form of step-like attractive discontinuities in the force profiles at separations ranging from 20 to 40 nm, caused by bridging of microscopic bubbles residing at the surfaces. The shape or range of these discontinuities are not significantly affected by replacement of the water with either 1 mM or 1 M NaCl solutions. The origin of the charges causing the electrostatic double-layer interaction is unclear, but some possible causes are discussed.

本文言語英語
ページ(範囲)391-397
ページ数7
ジャーナルJournal of Colloid And Interface Science
235
2
DOI
出版ステータス出版済み - 3 15 2001
外部発表はい

All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • 生体材料
  • 表面、皮膜および薄膜
  • コロイド化学および表面化学

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