Eur. Phys. J. E 4, 45-50

Diblock copolymers adsorbed at a water-oil interface

P. Omarjee¹, P. Hoerner², G. Riess², V. Cabuil³ and O. Mondain-Monval¹.

¹  Centre de Recherche Paul Pascal-CNRS, Av. A. Schweitzer, 33600 Pessac, France
²  Ecole Nationale Supérieure de Chimie de Mulhouse, 3 rue A. Werner, 68093 Mulhouse Cedex, France
³  Laboratoire LI2C - Colloïdes Magnétiques, Université P. et M. Curie, 4 Place Jussieu, 75252 Paris, Cedex 05, France

mondain@crpp.u-bordeaux.fr

(Received 5 May 2000 and Received in final form 6 July 2000)

Abstract
We probe the conformation of a diblock copolymer layer adsorbed at the surface of water-in-oil emulsion droplets at various concentration of a molecular surfactant. The diblock copolymer is made of a hydrophobic polybutadiene part linked to a hydrophilic polyethylene oxide one. The measure provides the equilibrium thickness of the polymer layer that is obtained with two different techniques, i.e. dynamic light scattering and force measurements. The structure of the layer is shown to change from a "mushroom"conformation in which the adsorbed chains form independent Gaussian coils to a conformation where they interact and extend in the continuous phase. The transition from one regime to the other is progressive as the ratio surfactant/polymer bulk concentration varies.

PACS
82.70.Dd - Colloids.
36.20.-r - Macromolecules and polymer molecules.
68.10.-m - Fluid surfaces and fluid-fluid interfaces.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001