title: Interaction and flocculation of spherical colloids wetted by a surface-induced corona of paranematic order.
abstract: Particles dispersed in a liquid crystal above the nematic-isotropic phase transition are wetted by a surface-induced corona of paranematic order. Such coronas give rise to pronounced two-particle interactions. In this paper, we report details on the analytical and numerical study of these interactions published recently [Phys. Rev. Lett. 86, 3915 (2001)]. We especially demonstrate how for large particle separations the asymptotic form of a Yukawa potential arises. We show that the Yukawa potential is a surprisingly good description for the two-particle interactions down to distances of the order of the nematic coherence length. Based on this fact, we extend earlier studies on a temperature induced flocculation transition in electrostatically stabilized colloidal dispersions [Phys. Rev. E 61, 2831 (2000)]. We employ the Yukawa potential to establish a flocculation diagram for a much larger range of the electrostatic parameters, namely, the surface charge density and the Debye screening length. As a distinguished feature, a kinetically stabilized dispersion close to the nematic-isotropic phase transition is found.
authors.affiliation: LBHP (UMR 7057), Université Paris 7-Denis Diderot and FR CNRS 2438 Matière et Systèmes Complexes, Case 7056, 2 place Jussieu, F-75251 Paris cedex 05, France. galatola@ccr.jussieu.fr
authors.forename: Paolo
authors.initials: P
authors.lastname: Galatola
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Fournier
authors.forename: Holger
authors.initials: H
authors.lastname: Stark