1,749 research outputs found
Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic Surfactants
We present a model treating the kinetics of adsorption of soluble
surface-active molecules at the interface between an aqueous solution and
another fluid phase. The model accounts for both the diffusive transport inside
the solution and the kinetics taking place at the interface using a free-energy
formulation. In addition, it offers a general method of calculating dynamic
surface tensions. Non-ionic surfactants are shown, in general, to undergo a
diffusion-limited adsorption, in accord with experimental findings.Comment: 6 pages, 3 figures, see also cond-mat/960814
Unstable topography of biphasic surfactant monolayers
We study the conformation of a heterogeneous surfactant monolayer at a
fluid-fluid interface, near a boundary between two lateral regions of differing
elastic properties. The monolayer attains a conformation of shallow, steep
`mesas' with a height difference of up to 10 nm. If the monolayer is
progressively compressed (e.g. in a Langmuir trough), the profile develops
overhangs and finally becomes unstable at a surface tension of about K(delta
c_0)^2, where (delta c_0) is the difference in spontaneous curvature and K a
bending stiffness. We discuss the relevance of this instability to recently
observed folding behavior in lung surfactant monolayers, and to the absence of
domain structures in films separating oil and water in emulsions.Comment: 7 pages, 7 figures, LaTex using epl.cls, accepted for Europhys Let
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