title: Quantification of specific anion binding to non-ionic Triton X-100 micelles.
abstract: Anion binding to nonionic micelles was quantified by self-diffusion. Four anions were probed by multinuclear PGSTE NMR measurements in a Triton X-100 micellar aqueous solution. The salt concentration used was sufficiently low to avoid any micellar growth affecting surface curvature. The micellar aggregates that provide a model surface are uncharged with hydrophilic headgroups so that electrostatic ion surface interactions play little or no role in prescribing specific anion binding. Anionic affinity to the micellar surface followed a Hofmeister series, (CH(3))(2)AsO(2)(-) ≫ CH(3)COO(-) > H(2)PO(4)(-) > F(-). The observed ion specificity is rationalized by calling into play the nonelectrostatic interactions occurring between the anions and the micellar surface.
authors.affiliation: Department of Chemical Science, University of Cagliari, CNBS, and CSGI, ss 554, bivio Sestu, 09042 Monserrato (CA), Italy. murgias@unica.it
authors.forename: Sergio
authors.initials: S
authors.lastname: Murgia
authors.forename: Maura
authors.initials: M
authors.lastname: Monduzzi
authors.forename: Gerardo
authors.initials: G
authors.lastname: Palazzo
mesh_terms: D000838:Anions; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D017830:Octoxynol / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000838:Anions; D008823:Micelles; D013501:Surface-Active Agents; D017830:Octoxynol