G. Urbinavillalba et al., THEORETICAL-STUDY ON THE STRUCTURE AND INTERFACIAL-AREAS OF NONYL PHENOL ETHOXYLATED SURFACTANTS, Colloids and surfaces. A, Physicochemical and engineering aspects, 99(2-3), 1995, pp. 207-220
A structural, molecular mechanics and molecular dynamics study of the
properties of nonyl phenol ethoxylated surfactants (NPE) is presented.
In the first part, structural AM1 calculations on CH3(CH2)(8)-C6H4-O-
(CH2CH2O)(m)-H(NPE(m)) surfactants, where m = 2, 5, 8, 9, 11, 12, 13 a
nd 14 units, were carried out, and the variation of the molecular prop
erties was observed as a function of the molecular length. The magnitu
de of the intermolecular energies between pairs of NPE(m), NE(m), and
aryl-substituted NPE(m) surfactant molecules has also been studied, an
d the effect of the ionization potential on the intermolecular interac
tion between these surfactants is discussed. In the second part, the i
nterfacial areas of nonyl phenol triethoxylated surfactants were deter
mined using short-time molecular dynamics calculations on ternary syst
ems composed of a surfactant monolayer located at a heptane/water inte
rface. A novel energetic description of a surfactant monolayer at an o
il/water interface is presented. This expression can be simply paramet
rized with the aid of molecular dynamics simulations.