Bob Evans de l’Université de Bristol, présentera un séminaire le 3 avril 2014 à 14h00 dans la bibliothèque du laboratoire PHENIX (7e étage, bâtiment F, porte 754) intitulé :
Phase Behaviour of Colloids Suspended in a Near-Critical Solvent : a Simple Model
Résumé
In 1978 Fisher and de Gennes predicted the existence of long-ranged solvent–mediated (SM) interactions between two colloidal particles suspended in a molecular solvent near its critical point. As a result of recent theory and simulation studies by several groups and direct experimental measurements, these (universal) SM forces, often termed critical Casimir forces, are quite well-understood. Largely unexplored is the colloidal phase behaviour that arises in a dense suspension where the correlation length of the near-critical solvent is comparable with the radius of the colloidal particles. We address this issue using a simple two-dimensional lattice gas for the solvent and Brownian disks for the adsorbing colloids. We find the many-body SM interactions that result drive colloidal gas-liquid and gas-solid phase transitions where the solvent is supercritical. Our simulation study, supported by a mean-field treatment, provides some insight into possibilities for colloidal self-assembly mediated by solvent criticality.
Work with J.R.Edison, N.Tasios, S.Belli, R.van Roij and M.Dijkstra (Utrecht University).
