INVESTIGADORES
SCHULZ Erica Patricia
artículos
Título:
Intermediate Structures for Higher Level Arrangements: Catching Disk-Like Micelles in Decane Phosphonic Acid Aqueous Solutions
Autor/es:
ERICA P. SCHULZ; ÁNGEL PIÑEIRO GUILLÉN; JOSÉ LUIS RODRÍGUEZ; ROSANNA M. MINARDI; MARISA A. FRECHERO; PABLO C. SCHULZ
Revista:
JOURNAL OF PHYSICAL CHEMISTRY B - (Print)
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2013 vol. 117 p. 6231 - 6240
ISSN:
1520-6106
Resumen:
It has been proposed that disk-like micelles may be precursors to the formationof lamellar liquid crystals. The possibility of obtaining n-decane phosphonic acid (DPA) disk-like micelles in aqueous solution without the addition of a second ionic surfactant led us tostudy in detail the low-concentration range of this system by both a battery of experimentaltechniques and molecular dynamics (MD) simulations. The experimental results indicate thatpremicelles with some capacity to solubilize dyes are formed at 0.05 mM. The critical micelleconcentration (cmc) was found to be 0.260 ± 0.023 mM, much lower than that previouslyreported in the literature. Spherical micelles, which immediately grow, leading to disk-likemicelles, are probably formed at this concentration. At 0.454 ± 0.066 mM, disk-like micelles become unstable, giving rise to the formation of an emulsion of lamellar mesophase that dominates the system beyond 0.670 ± 0.045 mM. These experimental results were corroborated by MD simulations which, additionally, allow describing the structure of the obtained micelles at atomic level. The analysis of the MD trajectories revealed the presence of strong intermolecular hydrogen bonds between the surfactant headgroups, producing a compact polar layer with low water content. The formation of such H-bond network could explain the ability of this surfactant to form disk-like micelles at concentrations close to the cmc.