Conference paper

The Effect of Surfactants on Equilibrium Wetting

B. D. Summ ; Moscow State University, Department of CoUoidat Chemi stry, L eninsky Gory, Moscow 117234, USSR
Yu. V. Goryunov ; Moscow State University, Department of CoUoidat Chemi stry, L eninsky Gory, Moscow 117234, USSR
Z. N. Markina ; Moscow State University, Department of CoUoidat Chemi stry, L eninsky Gory, Moscow 117234, USSR

Abstract

Contact angles B0 of aqueous solutions contacting with hydrophilic
and hydrophobic surfaces were studied as affected by various
surfactants (alcohols, fatty acids, soaps) under conditions close to
thermodynamic equilibrium (in the atmosphere saturated with the
solution vapour). The conditions of transitions from limited wetting
(Bo > 0) to complete wetting, i.e. spontaneous spreading were also
studied. The effect of surfactants adsorption at the solid gas interface
was estimated from the isotherms of wetting tension W = cr1g
Cos B0 (cr1g is the surface tension of the solution) on the basis of
equation describing W as a function of concentration. It is shown
that adsorption of surfactants at the solid-gas interface markedly
affects wetting of hydrophilic materials. For hydrophobic materials
the effect is primarily due to adsorption of surfactants at the solid-
solution and solution-gas interfaces. It was found that equilibrium
wetting is affected by the type of adsorption at the solid surface
(physical or chemical adsorption). The influence of hydrocarbon
chain length in homological series of alcohols and fatty acids on
equilibrium contact angles and on transition to spontaneous spreading
was studied as well.

Keywords

Hrčak ID:

195902

URI

https://hrcak.srce.hr/195902

Publication date:

25.6.1979.

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