Magnetic soap films and magnetic soap foams

We investigate the physical properties of soap films and soap foams, the liquid phase of which contains a stable colloidal suspension of magnetic particles. The physical properties of such systems result from the equilibrium between the capillary forces, the gravity and the local magnetic forces. Therefore, they depend on the strength of an applied magnetic field or force, which makes it possible to act from outside on the system. We present the effect of the external field on the magnetic soap foams and films through two studies. First, we show that the dynamics of drainage in a freely suspended magnetic soap film is modified by an external magnetic field. Second, we present the control, via an external magnetic force, of the structure adopted by a monodisperse foam in a cylindrical tube. Those studies open possible applications of the ferrofluid foam, in the field of technological applications, but also as a model experimental system to study the drainage, the dynamical rheology, and the stability of soap foams. (c) 2005 Elsevier B.V. All rights reserved.