Condensed Matter Seminar

Jerzy Blawzdziewicz
Yale University

Thursday, October 12, 2006
1:00 pm in SPL 52

Stepwise drainage of thin liquid films stabilized by colloidal particles

Abstract: Particle-stabilized films do not drain continuously but, instead, they undergo a series of stepwise transitions between states of different thickness. This behavior stems from the oscillatory structural forces produced by the particles present in the film. We show that both the normal and tangential components of these forces are essential for description of equilibrium and non-equilibrium film properties. In our approach the film is described using a quasi-two dimensional thermodynamic formalism where the key intensive parameters are the normal pressure and the effective film tension. The latter quantity is obtained from the difference between the normal and tangential pressure components. Our formalism is also generalized for films out of equilibrium. In the linear-response regime, the film dynamics is characterized by the shear and extension viscosity coefficients as well as by two kinetic coefficients relating the particle flux to the gradients of the particle chemical potential and normal osmotic pressure in the film. (In contrast, in bulk suspensions there is no independent osmotic-pressure contribution to the particle flux.) Numerical results for the effective equations of state, phase-equilibrium conditions, and linear transport coefficients are presented for a film stabilized by a suspension of hard-spheres.