Traveling strings of active dipolar colloids

Bristol Research (University of Bristol)

Abstract

We study an intriguing new type of self-assembled active colloidal polymer system in 3D. It is obtained from a suspension of Janus particles in an electric field that induces parallel dipoles in the particles as well as self-propulsion in the plane perpendicular to the field. At low packing fractions, in experiment, the particles self-assemble into 3D columns that are self-propelled in 2D. Explicit numerical simulations combining dipolar interactions and active self-propulsion find an activity dependent transition to a string phase by increasing dipole strength. We classify the collective dynamics of strings as a function of rotational and translational diffusion. Using an anisotropic version of the Rouse model of polymers with active driving, we analytically compute the strings' collective dynamics and centre of mass motion, which matches simulations and is consistent with experimental data. We also discover long range correlations of the fluctuations along the string contour that grow with the active persistence time, a purely active effect that disappears in the thermal limit.

Authors 5

1. Xichen Chao

   University of Bristol

   Affiliation as printed

   School of Mathematics , University of Bristol -Bristol BS8 1UG , UK

2. Katherine Skipper

   University of Bristol

   Affiliation as printed

   H.H. Wills Physics Laboratory , Tyndall Avenue , Bristol , BS8 1TL , UK

3. C. Patrick Royall

   Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · University of Bristol · Gulliver · ESPCI Paris

   Affiliation as printed

   Gulliver UMR CNRS 7083 , ESPCI Paris , Universit´e PSL , 75005 Paris , France

   H.H. Wills Physics Laboratory , Tyndall Avenue , Bristol , BS8 1TL , UK

4. Silke Henkes Aachen Lorentz Institute

   Leiden University · University of Bristol

   Affiliation as printed

   Lorentz Institute , LION , Leiden University -Leiden 2333 CA , NL

   School of Mathematics , University of Bristol -Bristol BS8 1UG , UK

5. Tanniemola B. Liverpool

   University of Bristol

   Affiliation as printed

   School of Mathematics , University of Bristol -Bristol BS8 1UG , UK