J. Phys. II France
Volume 2, Numéro 2, February 1992
Page(s) 235 - 247
DOI: 10.1051/jp2:1992127
J. Phys. II France 2 (1992) 235-247

Statistical mechanics of random bicontinuous phases

P. Pieruschka and S. Marcelja

Department of Applied Mathematics, Institute of Advanced Studies, The Australian National University, Canberra, A.C.T. 2601, Australia

(Received 10 July 1991, accepted 22 October 1991)

We consider a random wave description of bicontinuous microemulsions, where the structure is specified by a correlation length $\xi$ and a preferred wave vector k0. The entropy of the system is calculated as the information content of a random field with an experimentally determined spectral distribution. Together with the elastic energy which has been previously derived by Teubner, we can minimise the free energy of the system and thus estimate the value of the elastic modulus $\kappa$ of the film. For example, in water - toluene - SDS/butanol microemulsions the parameters $\xi$ and k0 obtained from fits to the neutron scattering data lead to values for $\kappa$ of about two units of kT.

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