Selfassembly of model surfactants

In order to check whether the model surfactants selfassemble a series of simulations has been performed. All those simulation were done at constant width and height of the simulation box and constant overall density, but varying surfactant concentration c. The figures below show on of those series. In this case you see an increasing concentration of flexible ht2-surfactants in a 12x12x15 box. The overall density is 2/3.

Micelle out of 10 surfactants Micelle out of 20 surfactants Micelle out of 60 surfactants
Cylindric micelle of 80 surfactants flatten cylindric micelle out of 100 surfactants Bilayer out of 110 surfactants
The movie (770 kByte, click on the picture one the left) shows the process of selfassembly for the bilayer formation. It is the same system as above.

In the simulations using different systems (HT2 and H3(T4)2) similar aggregates has been observed.

Conclusion

It has been proven that the model surfactants selfassemble into aggregates, especially into micelles and bilayers. Due to constraints in the available CPU-time it wasn't possible to determine any cmc. However, is definitely a lot smaller than 3%, since the process of selfassembly is even in systems with only 5 surfactants (i.e. 3 %) rather fast.

For more details, see my publication [1-3].

Literature:

  1. R. Goetz; PhD-thesis, Universität Potsdam 1997.
  2. R. Goetz, R. Lipowsky; J. Chem. Phys. 108, (1998), 7397-7409
  3. R. Goetz, R. Lipowsky; Phys. Rev. Letters 82, (1999), 221-224

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