INQUISUR 21779
INSTITUTO DE QUIMICA DEL SUR
Unidad Ejecutora - UE
artículos
Título:
Thermodynamic and elastic fluctuation analysis of langmuir mixed monolayers composed by dehydrocholic acid (HDHC) and didodecyldimethylammonium bromide (DDAB)
Autor/es:
PAULA V. MESSINA, GERARDO PRIETO, JUAN MANUEL RUSO, MARCOS D. FERNÁNDEZ-LEYES, PABLO C. SCHULZ, FÉLIX SARMIENTO
Revista:
COLLOIDS AND SURFACES B-BIOINTERFACES
Editorial:
Elsevier
Referencias:
Año: 2010 vol. 75 p. 34 - 41
ISSN:
0927-7765
Resumen:
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The physicochemical and
elastic properties of Langmuir mixed monolayers composed by dehydrocholic acid
(HDHC) and didodecyldimethylammonium bromide (DDAB) were evaluated. The
experiments were performed with a constant surface pressure penetration
Langmuir balance based on Axisymmetric Drop Shape Analysis (ADSA).
The behavior of such
amphiphiles in monolayerwasclearly non-ideal and would be seriously influenced by
the amount of HDHCmolecules present. The presence of bile acid type molecules
caused the monolayer be more condensed (Ac
diminution) and the intermolecular attractive
interactions be stronger (high ε0 values). This
fact would be related to H-bond formation between water and carboxilate and
carbonile groups in the cholesteric ring and agreed with the existence of
laterally structured microdomains at the monolayer (determined by the analysis
of the first virial coefficient, b0 < 1, of
the state equation). The miscibility of both surfactants in the monolayer,
their high bulk hydrophobicity (pc >35mJm−2) just with
the obtained negative values of the free energy of mixing DGmix, and the excess
second virial coefficient (b1)E obtained
allows us to infer that net attractive interaction existed between HDHC and DDAB
molecules at the monolayer and that mixed systems would be able to be used in
the formulation of supramolecular assemblies.
