SIMPLE THEORETICAL FRAMEWORK FOR A SYSTEMATIC MOLECULAR-DYNAMICS STUDY OF THE INTERFACIAL PROPERTIES OF OIL WATER SYSTEMS IN THE PRESENCE OF SURFACTANT MOLECULES/
G. Urbinavillalba et I. Reif, SIMPLE THEORETICAL FRAMEWORK FOR A SYSTEMATIC MOLECULAR-DYNAMICS STUDY OF THE INTERFACIAL PROPERTIES OF OIL WATER SYSTEMS IN THE PRESENCE OF SURFACTANT MOLECULES/, Colloids and surfaces. A, Physicochemical and engineering aspects, 106(2-3), 1996, pp. 175-190
This paper presents a simple theoretical methodology for a systematic
molecular dynamics study of the interfacial properties of oil/water/su
rfactant systems. This formalism is based on the appropriate definitio
n and classification of the different energy terms which contribute to
the free energy of the ternary system, and thus, to the chemical pote
ntials of the surfactants in oil, water, and at the oil/water interfac
e. Using molecular dynamics techniques over interfacial and bulk model
s atomistically described, series expansions fittings of those energy
terms as a function of surfactant concentration can be obtained, and a
simple thermodynamic expression for the free energy of the whole syst
em results. This report is solely related with the development of that
free-energy expression along with analytical formulae for the surface
excess, the interfacial tension, and the chemical potentials of a sur
factant in oil, water, and at the oil/water interface. The application
of this theoretical approach to the study of the interfacial properti
es produced by chemically different surfactants, and a systematic stud
y of the effect of the formulation variables on the interfacial behavi
our of an oil/water system, will be forwarded in future reports.