Effect of the hydrophilic size on the structural phases of aqueous nonionic gemini surfactant solutions

Mu Ping Nieh, Sanat K. Kumar, Raymond H. Fernando, Ralph H. Colby, John Katsaras

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Aggregate structures of aqueous nonionic Gemini surfactant solutions, α,α′-[2,4,7,9-tetramethyl-5-decyne-4,7-diyl] bis[ω-hydroxyl-polyoxyethylene] with three different length polyoxyethylenes (i.e., 10, 20, and 30 ethylene oxide monomers, denoted from now on as S-10, S-20, and S-30, respectively), are investigated using small angle neutron scattering, dynamic light scattering, and fluorescence spectroscopy. For S-10 at low surfactant concentrations (C s < 0.9 wt %), large "clusters", with an average hydrodynamic radius 〈RH〉 > 40 nm, are found to coexist with monomers. At intermediate C s (0.9 < C s < 2 wt %), some clusters break down forming micelles, with an (R H) ∼2-3 nm, while the remaining clusters coexist with micelles. Increasing C s further (>2 wt %) results in a pure micellar phase with little or no clusters present. S-20 and S-30 mixtures, on the other hand, differ from S-10 in that irrespective of surfactant concentration, large clusters and small monomers/dimers are found to coexist, while there is no direct evidence for the presence of micelles.

Original languageEnglish (US)
Pages (from-to)9061-9068
Number of pages8
JournalLangmuir
Volume20
Issue number21
DOIs
StatePublished - Oct 12 2004

All Science Journal Classification (ASJC) codes

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

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