Morphology and mechanical properties of surfactant aggregates at water-silica interfaces: Molecular dynamics simulations

Kunal Shah, Patrick Chiu, Mayank Jain, José Fortes, Brij Moudgil, Susan B. Sinnott

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Dilute and concentrated surfactant systems at the solid-liquid interface are examined using classical molecular dynamics simulations. Particular emphasis is placed on under standing how surfactants aggregate and form the micellar structure, how micelles change shape at high concentrations in aqueous media and in the presence of hydrophilic surfaces, and at what force this micellar structure breaks apart during indentation of micelle-covered surfaces with a proximal probe microscope tip. The specific system of interest is C 12TAB (n-dodecyltrimethylammonium bromide) surfactant in an aqueous medium that is modeled with empirical potentials. The simulations predict that the micelle structure in water is compact and either spherical or elliptical in shape. In the presence of a hydrophilic surface of silica, the structure evolves into a flat elliptical shape, in agreement with experimental findings. The simulated indentation of the micelle/silica system causes the micelle to break apart at an indentation force of about 1 nN and form a surfactant monolayer. The predicted force curve is in excellent agreement with experimental measurements.

Original languageEnglish (US)
Pages (from-to)5337-5342
Number of pages6
JournalLangmuir
Volume21
Issue number12
DOIs
StatePublished - Jun 7 2005

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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