Direct visualization of surfactant hemimicelles by force microscopy of the electrical double layer

Srinivas Manne, J. P. Cleveland, H. E. Gaub, G. D. Stucky, P. K. Hansma

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Abstract

The morphology of ionic surfactant molecules adsorbed from aqueous solution onto hydrophobic substrates has been determined by atomic force microscopy. Near the critical micelle concentration (cmc), noncontact imaging using double-layer repulsion between the tip and sample shows parallel, epitaxially oriented stripes spaced apart by about twice the surfactant length. This represents the first direct imaging of 'hemimicelles', liquid-crystalline aggregates of amphiphilic molecules (analogous to bulk micelles) which form at interfaces. The striped pattern is indicative of hemicylindrical hemimicelles, which is further corroborated by images of the monolayer adsorbate (in contact mode) below the cmc. Our results suggest that the hemimicelle structure is templated by the epitaxially bound monolayer in contrast with previous interpretations of the adsorption mechanism.

Original languageEnglish (US)
Pages (from-to)4409-4413
Number of pages5
JournalLangmuir
Volume10
Issue number12
Publication statusPublished - Dec 1994
Externally publishedYes

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

Cite this

Manne, S., Cleveland, J. P., Gaub, H. E., Stucky, G. D., & Hansma, P. K. (1994). Direct visualization of surfactant hemimicelles by force microscopy of the electrical double layer. Langmuir, 10(12), 4409-4413.