Contribution of 1H NMR to the investigation of the adsorption of cationic Gemini surfactants with oligooxyethylene spacer group onto silica

Anissa Bendjeriou-Sedjerari, Gaelle Derrien, Clarence Charnay*, Jerzy Zajac, Louis Charles De Menorval, Marc Lindheimer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The present study aims to investigate the behavior of a series of cationic Gemini surfactants with a hydrophilic spacer at liquid-gas and solid-liquid interfaces, with particular emphasis on the effect of spacer length. Gemini surfactants containing two quaternary ammonium groups bound by an ethylene oxide spacer chain, referred to as 12-EOx-12 with x = 1, 3, 7 and 12 were synthesized. Surface tension measurements were used to show that the hydrophilic spacer with oxyethylene moieties was not fully extended at the air-water interface. With increasing the spacer group size, it became sufficiently flexible to adopt a particular conformation with a loop at the water side of the interface. A combined study by adsorption isotherm measurements and 1H NMR spectroscopy allowed a detailed description of the adsorption mechanism of these investigated 12-EOx-12 surfactants, with NMR providing more precise information on the conformation of hydrophilic spacer at the solid-liquid interface. Binding to the silica surface involved one cationic headgroup for the surfactants with a short spacer and the two headgroups for the ones with a long spacer. The number of charged surface sites was estimated by considering the dimeric surfactant as a "molecular ruler." The small density of adsorption sites gave rise to the formation of pinned surface micelles.

Original languageEnglish (US)
Pages (from-to)281-287
Number of pages7
JournalJournal of Colloid And Interface Science
Volume331
Issue number2
DOIs
StatePublished - Mar 15 2009

Keywords

  • Gemini surfactant
  • H NMR spectroscopy
  • Interfacial aggregation
  • Micellization
  • Surface tension

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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