INVESTIGADORES
FALCONE Ruben Dario
artículos
Título:
Solvent Blends can Control Cationic Reversed Micellar Interdroplet Interactions. The Effect of n-Heptane:Benzene Mixture on BHDC Reversed Micellar Interfacial Properties: Droplet Sizes and Micropolarity.
Autor/es:
FEDERICO M. AGAZZI; R. DARIO FALCONE; JUANA J. SILBER; N. MARIANO CORREA
Revista:
JOURNAL OF PHYSICAL CHEMISTRY B
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2011 vol. 115 p. 12076 - 12084
ISSN:
1089-5647
Resumen:
We have investigated, for the first time, the effect of
the composition of the nonpolar organic media on the benzyl-nhexadecyl-
dimethylammonium chloride (BHDC) reversed micelles
(RMs) properties at fixed temperature. To achieve this goal
we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium
betaine (QB) as absorption probe and dynamic light
scattering (DLS), to monitor droplet sizes, interfacial micropolarity,
and sequestrated water structure of water/BHDC/n-heptane:
benzene RMs. DLS results confirm the formation of the water/
BHDC/n-heptane:benzene RMs at every n-heptane mole fraction
(XHp) investigated, that is, XHp = 0.00, 0.13, 0.21, 0.30, and 0.38.
Also, DLS was used to measure the RMs diffusion coefficient and
to calculate the apparent droplet hydrodynamic diameter (dApp) at
different compositions of the nonpolar organic medium. The data
suggest that as the n-heptane content increases, the interdroplet
attractive interactions also increase with the consequent increment
in the droplet size. Moreover, the interdroplet attractive interactions
can be switched on (increased) or switched off (decreased) by formulation of appropriate n-heptane:benzene mixtures.
Additionally, QB spectroscopy was used to obtain the operational critical micellar concentration (cmc) and to investigate both the
RMs interfacial micropolarity and the sequestrated water structure in every RMs studied. The results show that BHDC RMs are
formed at lower surfactant concentration when n-heptane or water content increases. When the interdroplet interaction switches
on, the RMs droplet sizes growth expelling benzene molecules from the RMs interface, favoring the water-BHDC interaction at the
interface with the consequent increases in the interfacial micropolarity. Therefore, changing the solvent blend is possible to affect
dramatically the interfacial micropolarity, the droplet sizes and the structure of the entrapped water.