Softening of the interactions between surfactant bilayers in a lamellar phase due to the presence of a polymer
Department of Applied Mathematics, Research School of Physical Sciences and
Australian National University, Canberra, A.C.T. 0200, Australia
Centre de Recherche Paul Pascal - CNRS, Avenue A. Schweitzer, 33600 Pessac,
Published online: 15 May 1999
The compressibility modulus of a lamellar phase containing a neutral polymer guest molecule was measured directly using a surface force apparatus. The system studied consisted of sodium dodecyl sulphate (SDS), pentanol, water and polyethylene glycol (PEG) . The lamellar phase was induced from a micellar phase in situ via a confinement induced isotropic to lamellar phase transition. This avoided problems resulting from the viscosity and turbidity normally characteristic of these lamellar phase samples. Increasing the amount of PEG resulted in a marked decrease in the layer compressibility modulus indicating a decrease in the repulsive forces between the lamellae. The origin of such a phenomenon is discussed in terms of different mechanisms including depletion interactions, bridging interactions and modification of the electrostatic interaction between the lamellae by the polymer.
PACS: 82.70.-y – Disperse systems / 64.70.Md – Transitions in liquid crystals / 61.25.Hq – Macromolecular and polymer solutions; polymer melts; swelling
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999