Phase Separation by Entanglement of Active Polymerlike Worms

Area of Science:

• Active matter physics
• Soft condensed matter
• Biophysics

Background:

• Living organisms can exhibit collective behaviors analogous to physical systems.
• Active polymers, such as T. tubifex worms, represent a unique class of matter with self-propulsion.
• Understanding self-organization in active matter is crucial for fields ranging from robotics to developmental biology.

Purpose of the Study:

• To investigate the aggregation and phase separation dynamics of Tubifex tubifex worms.
• To characterize the growth kinetics and underlying mechanisms of this active phase separation.
• To compare the observed phenomena with conventional polymer phase separation and droplet coalescence.

Main Methods:

• Observation of randomly dispersed Tubifex tubifex worms.
• Analysis of aggregation into compact, entangled blobs.
• Measurement of growth kinetics and diffusion constants of worm blobs.

Main Results:

• Spontaneous aggregation of active worms into phase-separated blobs exhibiting power-law growth kinetics.
• Phase separation occurs via active motion and coalescence, not Ostwald ripening.
• Blob diffusion constant is independent of size, attributed to surface-driven active motion.

Conclusions:

• Tubifex tubifex worms exhibit a novel phase separation mechanism distinct from passive systems.
• The size-independent diffusion of worm blobs suggests a unique growth process driven by surface activity.
• This study highlights a potentially unique phase-separation mechanism specific to active polymers.