Fig. 5: Persistent rotation in a metastable S-shaped configuration and its transition to a stable C-shaped configuration.
From: Emergent dynamics due to chemo-hydrodynamic self-interactions in active polymers
Longer active polymers transiently adopt S-shaped configurations with associated characteristic A hydrodynamic flow fields and B symmetry broken chiral chemical fields (Supplementary Videos SV13 and SV14). C In this metastable configuration the polymers undergo persistent rotation and transition spontaneously into the stable C-shaped configuration. Top: The top panel (left to right) shows time snapshots of cross-polarised microscopy images of active polymer chain configurations (all scale bars are 50 μm). The instantaneous propulsion directions of droplets in the chain can be visualised with the help of a nematic director pointing in the propulsion direction. The initial time (t = 0s and 40s) frames show that active chain rotation in transient S-configuration (curved red arrows show direction of instantaneous rotation). At t  ≈ 168s, the active chain completely transitions to a stable C-configuration and propels along a selected direction (indicated by the white arrow). Note that the transition time (from S to C-configuration) can be different for different chain lengths. Bottom: The above phenomena are reproduced in our simulations. We see the rotation (curved red arrows) in the S-configuration (t = 0s and t = 40s), and a purely linearly translating (long black arrow) rigid chain at t = 168s.
