title: Self-Diffusiophoresis of Janus Particles in Near-Critical Mixtures.
abstract: We theoretically study the self-propulsion of a laser-heated Janus particle in a near-critical water-lutidine mixture, and we relate its velocity v_{p} and squirmer parameter β to the wetting properties of its two hemispheres. For nonionic surface forces, the particle moves the active cap at the front, whereas a charged hydrophilic cap leads to backward motion, in agreement with the experiment. Both v_{p} and β show nonmonotonic dependencies on the heating power, and they may even change sign. The variation of β is expected to strongly affect the collective behavior of dense squirmer systems.
authors.affiliation: Laboratoire Ondes et Matière d'Aquitaine, Université de Bordeaux and CNRS, 351 cours de la Libération, 33405 Talence, France.
authors.forename: Alois
authors.initials: A
authors.lastname: Würger