Emergence of Order in Chemically Active Droplets: Temporal Dynamics and Collective Behavior

Collective behaviors such as swarming,
chemical signaling, and
clustering are fundamental to biological microorganisms, enabling
hierarchical colony formation, coordinated motion, and enhanced nutrient
accessibilitycrucial for their survival. Over the past few
decades, active droplets have emerged as valuable synthetic analogues,
effectively replicating key biological attributes and serving as ideal
platforms for investigating collective phenomena. This research explores
the collective behavior of 4-cyano-4′-pentylbiphenyl (5CB)
oil droplets across varying Péclet (Pe) numbers.
At high Pe, droplets exhibit a pusher mode of propulsion
and form dynamic chain-like patterns. Decreasing Pe enhances repulsive interactions among droplets, resulting in the
inhibition of clustering. These repulsive interactions, mediated
by chemical fields, lead to the emergence of an ordered structure
at low Pe. Furthermore, we also illustrate how active
droplets of larger size efficiently navigate within such a soft structured
environment. These findings significantly contribute to our comprehension
of self-organized phenomena in active matter systems.