Competition between surfactant micellization and complexation by cyclodextrin

M. Cepeda, R. Daviña, L. García-Río, M. Parajó, P. Rodríguez-Dafonte, M. Pessêgo

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Supramolecular property systems composed of alkyltrimethylammonium surfactants and β-cyclodextrin were studied by means of a chemical probe. Solvolysis of 4-methoxybenzenesulfonyl chloride (MBSC) was used in the mixed systems with the aim of being able to determine the concentration of uncomplexed cyclodextrin in equilibrium with the micellar system. The surfactants used enabled us to vary the length of the hydrocarbon chain between 6 and 18 carbon atoms. In all cases the existence of a significant concentration of uncomplexed CD was observable in equilibrium with the micellar system. The percentage of uncomplexed cyclodextrin increases both on increasing and decreasing the surfactant alkyl chain length, being minimal for alkyl chains between 10-12 carbon atoms. This behavior is a consequence of two simultaneous processes: complexation of surfactant monomers by the cyclodextrin and surfactant self-assembly to form micellar aggregates. By using Gibbs free energies for micellization and surfactant complexation by β-CD, we can quantitatively explain the observed behavior.

Original languageEnglish
Pages (from-to)1093-1102
Number of pages10
JournalOrganic and Biomolecular Chemistry
Volume11
Issue number7
DOIs
Publication statusPublished - 21 Feb 2013

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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