Abstract:
We segregate and report experimentally for the first time the polar and dispersive interfacial energy
components of complex nanocolloidal dispersions. In the present study, we introduce a novel
inverse protocol for the classical Owens Wendt method to determine the constitutive polar and
dispersive elements of surface tension in such multicomponent fluidic systems. The effect of
nanoparticles alone and aqueous surfactants alone are studied independently to understand the role
of the concentration of the dispersed phase in modulating the constitutive elements of surface
energy in fluids. Surfactants are capable of altering the polar component, and the combined particle
and surfactant nanodispersions are shown to be effective in modulating the polar and dispersive
components of surface tension depending on the relative particle and surfactant concentrations as
well as the morphological and electrostatic nature of the dispersed phases. We observe that the
combined surfactant and particle colloid exhibits a similar behavior to that of the particle only
case; however, the amount of modulation of the polar and dispersive constituents is found to be
different from the particle alone case which brings to the forefront the mechanisms through which
surfactants modulate interfacial energies in complex fluids. Accordingly, we are able to show that
the observations can be merged into a form of quasi-universal trend in the trends of polar and dispersive components in spite of the non-universal character in the wetting behavior of the fluids. We
analyze the different factors affecting the polar and dispersive interactions in such complex colloids, and the physics behind such complex interactions has been explained by appealing to the
classical dispersion theories by London, Debye, and Keesom as well as by Derjaguin-LandauVerwey-Overbeek theory. The findings shed light on the nature of wetting behavior of such
complex fluids and help in predicting the wettability and the degree of interfacial interaction with a
substrate in such multicomponent nanocolloidal systems.
