From aggregative adsorption to surface depletion: aqueous systems of CnEm amphiphiles at hydrophilic surfaces

Gernot Rother, Dirk Müter, Henry Bock, Martin Schoen, Gerhard H. Findenegg

Research output: Contribution to journalArticle

2 Citations (Scopus)
24 Downloads (Pure)

Abstract

Adsorption of a short-chain nonionic amphiphile (C6E3) at the surface of mesoporous silica glass (CPG) was studied by a combination of adsorption measurements and mesoscale simulations. Adsorption measurements covering a wide composition range of the C6E3 + water system show that no adsorption occurs up to the critical micelle concentration, at which a sharp increase of adsorption is observed that is attributed to ad-micelle formation at the pore walls. Intriguingly, as the concentration is increased further, the surface excess of the amphiphile begins to decrease and eventually becomes negative, which corresponds to preferential adsorption of water rather than amphiphile at high amphiphile concentrations. The existence of such a surface-azeotropic point has not previously been reported in the surfactant adsorption field. Dissipative particle dynamics simulations were performed to reveal the structural origin of this transition from aggregative adsorption to surface depletion. The simulations indicate that this transition can be attributed to the repulsive interaction between head groups, causing depletion of the amphiphile in the region around the corona of the surface micelles.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalMolecular Physics
Early online date27 Mar 2017
DOIs
Publication statusE-pub ahead of print - 27 Mar 2017

Keywords

  • Adsorption
  • mesoscale simulations
  • nanopores
  • surface azeotrope
  • surfactant

ASJC Scopus subject areas

  • Biophysics
  • Molecular Biology
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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