Surfactants with colloids: Adsorption or absorption?

Gregory Smith, Isabelle Grillo, Sarah E Rogers, Julian Eastoe*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

19 Citations (Scopus)
244 Downloads (Pure)

Abstract

Hypothesis

The interaction of Aerosol OT (AOT) surfactant with systems of model colloids in nonaqueous solvents (water-in-oil microemulsions, surfactant-stabilized silica organosols, and sterically-stabilized PMMA latexes) is expected to be system specific. Two limiting cases are expected: adsorption, with surfactant located at the particle surfaces, or absorption, with surfactant incorporated into the particle cores.

Experiments

Two approaches have been used to determine how AOT is distributed in the colloidal systems. The stability of the colloids in different alkanes (heptane to hexadecane, including mixtures) has been studied to determine any effects on the colloid surfaces. Contrast-variation small-angle neutron scattering (SANS) measurements of the colloid cores and of AOT-colloid mixtures in colloid-matched solvent have also been performed. Normalization to account for the different scattering intensities and different particle radii have been used to enable a system-independent comparison.

Findings

AOT in water-in-oil microemulsions and surfactant-stabilized silica organosols is determined to be adsorbed, whereas, surprisingly, AOT in sterically-stabilized PMMA latexes is found to be absorbed. Possible origins of these differences are discussed.

Original languageEnglish
Pages (from-to)205-214
Number of pages10
JournalJournal of Colloid and Interface Science
Volume449
Early online date2 Feb 2015
DOIs
Publication statusPublished - 1 Jul 2015

Keywords

  • Colloids
  • Nonpolar solvents
  • Small-angle neutron scattering

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