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Surfactants-containing Aggregations in Effectively Two-dimensional Space in View of a Non-equilibrium Statistical-mechanical Model

Adam Gadomski 

University of Technology & Agriculture, Institute of Mathematics & Physics, al. Kaliskiego 7, Bydgoszcz 85-796, Poland


Systems comprising of entities with well-developed and electrically-active surfaces, like polymers, surfactants and colloids, are rich in entropically driven reactions. They may be not only between charged parts of the (bio)molecules but also they can be amongst the molecules, and even appear to be present amidst their clusters. Typically, they are of dipole-dipole type, induced dipolar and even quadrupolar (having an origin in the surface tension effect), to list but a few. Because of water ubiquitous character and role in such systems, a formation of hydrogen-bonding is to be mentioned here too. Due to merely amphiphilic character of the surfactants some specific additional reactions, rather slow or very instantaneous, can also be noticed [1].
All the reactions mentioned above readily help to cause emergence of aggregation phenomena, frequently mentioned in a phase-transition context, and quite extensively studied recently, mostly by means of experimental 2D Langmuir-like set-ups [2].
Mesoscopic nonequilibrium thermodynamics, starting from the well-known Gibbs equation, and making use of the concept of Onsager's reciprocity relations, and coefficients, looks capable of proposing a systematic description of the aggregation process in terms of surfactants' and surfactants clusters' sizes, size- and time-dependent diffusion-migration coefficient as well as by enabling a proper as well as unambiguous selection of the interaction potential governing the formation of the effectively two-dimensional system [3].
Such a choice can be proposed for the effectively two-dimensional interacting surfactants-containing assemblies, with the often applied under such physical circumstances screening Coulomb (DLVO) potential but in a limit of either the adequately chosen (high) temperature or when the conception of diluted-regime approximation really applies [4].

[1] A. Plonka, Dispersive kinetics, Prog. React. Kinetics & Mechanism 94, 89-175 (1998).
[2] V.M. Kaganer, H. Mouhwald, and P.Dutta, Structure and phase transitions in Langmuir monolayers, Rev. Mod. Phys. 71, 779-819 (1999).
[3] J.C. Earnshow and D.J. Robinson, Scale invariance in two-dimensional reaction-limited colloidal aggregation, J. Phys.: Condensed Matter 7, L397-L403 (1995).
[4] A. Gadomski and J.M. Rubi, On the two principal curvatures as potential barriers in a model of complex matter agglomeration, Chem. Phys. 293, 169-177 (2003).


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Presentation: Keynote lecture at SMCBS 2003 Workshop, by Adam Gadomski
See On-line Journal of SMCBS 2003 Workshop

Submitted: 2003-10-03 21:19
Revised:   2009-06-08 12:55