--------------------
- Nonequilibrium equation of state in suspensions of active colloids doi link

Auteur(s): Ginot Félix, Theurkauff Isaac, Levis D., Ybert Christophe, Bocquet Lydéric, Berthier L., Cottin-Bizonne Cécile

(Article) Publié: Physical Review, vol. 5 p.011004 (2015)
Texte intégral en Openaccess : arxiv


Ref HAL: hal-01132427_v1
Ref Arxiv: 1411.7175
DOI: 10.1103/PhysRevX.5.011004
WoS: 000349488400001
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
194 Citations
Résumé:

Active colloids constitute a novel class of materials composed of colloidal-scale particles locally converting chemical energy into motility, mimicking micro-organisms. Evolving far from equilibrium, these systems display structural organizations and dynamical properties distinct from thermalized colloidal assemblies. Harvesting the potential of this new class of systems requires the development of a conceptual framework to describe these intrinsically nonequilibrium systems. We use sedimentation experiments to probe the nonequilibrium equation of state of a bidimensional assembly of active Janus microspheres, and conduct computer simulations of a model of self-propelled hard disks. Self-propulsion profoundly affects the equation of state, but these changes can be rationalized using equilibrium concepts. We show that active colloids behave, in the dilute limit, as an ideal gas with an activity-dependent effective temperature. At finite density, increasing the activity is similar to increasing adhesion between equilibrium particles. We quantify this effective adhesion and obtain a unique scaling law relating activity and effective adhesion in both experiments and simulations. Our results provide a new and efficient way to understand the emergence of novel phases of matter in active colloidal suspensions.



Commentaires: 8 pages, 4 figs; to be published in Phys. Rev. X. Réf Journal: Phys. Rev. X 5, 011004 (2015)