Issue |
J. Phys. II France
Volume 5, Number 1, January 1995
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Page(s) | 103 - 112 | |
DOI | https://doi.org/10.1051/jp2:1995116 |
J. Phys. II France 5 (1995) 103-112
Measurement of the Interactions between Macroscopic Surfaces Inducing a First-Order Phase Transitions: the Sponge-Lamellar Transformation
D. A. Antelmi1, P. Kékicheff1 and P. Richetti21 Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, A.C.T. 0200, Australia
2 C.R.P.P.-C.N.R.S., Château Brivazac, Avenue Schweitzer, 33600 Pessac, France
(Received 12 September 1994, accepted in final form 2 November 1994)
Abstract
The interactions between two macroscopic walls immersed in an isotropic symmetric sponge phase (L
3) at different volume fractions,
, were studied with a surface force apparatus. At temperatures well below the lamellar (L
bulk transition, the force-distance profile is weakly oscillatory with a period that is twice the correlation length (
) of the L
3 phase measured from SAXS. The oscillations are superimposed on an exponentially attractive background with an order correlation
length of 2-4 cell sizes of the sponge structure. When the temperature is raised, a first-order phase transition to a lamellar
structure can be induced for separations below a threshold. Another oscillatory interaction results which has a period that
is twice the reticular distance for an L
phase of similar
. In addition, the thickness of the induced lamellar film increases (reversibly) with temperature. The compressibility modulus
extracted from the oscillatory interaction is consistent with that expected for lamellae stabilized by undulation forces.
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