title: The effects of counterion exchange on charge stabilization for anionic surfactants in nonpolar solvents.
abstract: OBJECTIVE
  Sodium dioctylsulfosuccinate (Aerosol OT or NaAOT) is a well-studied charging agent for model poly(methyl methacrylate) (PMMA) latexes dispersed in nonpolar alkane solvents. Despite this, few controlled variations have been made to the molecular structure. A series of counterion-exchanged analogs of NaAOT with other alkali metals (lithium, potassium, rubidium, and cesium) were prepared, and it was expected that this should influence the stabilization of charge on PMMA latexes and the properties of the inverse micelles.
  
  
  METHODS
  The electrophoretic mobilities of PMMA latexes were measured for all the counterion-exchanged AOT analogs, and these values were used to calculate the electrokinetic or ζ potentials. This enabled a comparison of the efficacy of the different surfactants as charging agents. Small-angle scattering measurements (using neutrons and X-rays) were performed to determine the structure of the inverse micelles, and electrical conductivity measurements were performed to determine the ionized fractions and Debye lengths.
  
  
  RESULTS
  Sodium AOT is a much more effective charging agent than any of the other alkali metal AOTs. Despite this, the inverse micelle size and electrical conductivity of NaAOT are unremarkable. This shows a significant non-periodicity in the charging efficiency of these surfactants, and it emphasizes that charging particles in nonpolar solvents is a complex phenomenon.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom. Electronic address: g.n.smith@sheffield.ac.uk.
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Smith
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Brown
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Craig
authors.initials: C
authors.lastname: James
authors.affiliation: Merck Chemicals Ltd, University Parkway, Chilworth, Southampton SO16 7QD, United Kingdom.
authors.forename: Roger
authors.initials: R
authors.lastname: Kemp
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Asad Muhammad
authors.initials: AM
authors.lastname: Khan
authors.affiliation: MAX IV Laboratory, Lund University, Box 118, SE-221 00 Lund, Sweden.
authors.forename: Tomás S
authors.initials: TS
authors.lastname: Plivelic
authors.affiliation: ISIS-STFC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Rogers
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom. Electronic address: julian.eastoe@bristol.ac.uk.
authors.forename: Julian
authors.initials: J
authors.lastname: Eastoe
mesh_terms: D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry*; D008672:Metals, Alkali / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D008672:Metals, Alkali; D013501:Surface-Active Agents; D004143:Dioctyl Sulfosuccinic Acid; D019904:Polymethyl Methacrylate
keywords: Electrophoresis; Nonpolar solvents; Polymer latexes; Small-angle scattering; Surfactants