INVESTIGADORES
CORREA Nestor Mariano
artículos
Título:
Molecular Dynamics Simulation of Water/BHDC Cationic Reverse Micelles. Structural Characterization, Dynamical Properties and the Inuence of the Solvent on the Intermicellar Interactions.
Autor/es:
FEDERICO AGAZZI; N. MARIANO CORREA; JAVIER RODRIGUEZ
Revista:
LANGMUIR
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2014 vol. 30 p. 9643 - 9653
ISSN:
0743-7463
Resumen:
We report results obtained from molecular
dynamics (MD) experiments of benzylhexadecyldimethylammonium
chloride (BHDC) cationic reverse micelles (RMs). In
particular we analyzed equilibrium and dynamical characteristics
of water/BHDC RMs in pure benzene, at two different
water/BHDC ratios (W0 = 5 and W0 = 10). The RMs appear as
elliptical aggregates with eccentricities close to ∼0.9. Analysis
of the different spatial correlations reveals three different spatial
domains in the RMs: a water inner pool, the surfactant
interface, and the external solvent. The calculated accessible
surface areas for the aqueous inner cores suggest a strong
penetration of solvent molecules within the micellar interface domains. Comparison between the density profiles of both RMs
shows an increment of the broadness in the distributions of all species at the interface, along with an increasing overlap between
the tail segments of the surfactant and benzene molecules as one considers larger micelles. For the dynamical side, the rotational
characteristic time scale for the confined water was found to be 1 order of magnitude larger than that of the bulk water. A similar
effect was also observed for hydrogen bond dynamics. Both retardation effects diminish with the size of the aggregate. To the
estimate the influence of the external solvent on the intermicellar interactions, free energy profiles for the coalescence process
between RMs of similar size in pure benzene and in a n-heptane/benzene mixture were also investigated. The results indicate that
the association process is facilitated by the presence of n-heptane in the external nonpolar phase. Comparison with previous
theoretical and experimental results is also carried out.