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Active Fluids Form System-Spanning Filamentary Networks
Paarth Gulati1, Fernando Caballero2, M Cristina Marchetti1,3
1University of California Santa Barbara, Department of Physics, Santa Barbara, California 93106, USA.
Physical Review Letters
|April 18, 2025
Summary
Active liquid crystals exhibit unique phase separation behaviors. This study reveals how active flows alter phase boundaries and create novel filamentous networks, offering new ways to control material interfaces.
Area of Science:
- Soft matter physics
- Active matter systems
- Liquid crystal dynamics
Background:
- Liquid-liquid phase separation is common in biological and soft matter systems.
- Active liquid crystals exhibit complex behaviors due to self-propelled motion.
- Interactions between phase separation and active flows are not fully understood.
Purpose of the Study:
- To investigate the interplay between phase separation and active flows in active liquid crystals.
- To analytically derive the effects of activity on phase boundaries.
- To characterize the emergent morphologies in active-passive fluid mixtures.
Main Methods:
- Continuum theory modeling
- Analytical derivation of phase boundary shifts
- Morphological analysis of phase-separated states
Main Results:
- Activity suppresses the phase boundary of the coexistence region due to a balance between active flows and diffusive fluxes.
- A novel mixed active phase emerges, characterized by a dynamic filamentous network.
- This filamentous network traps passive fluid droplets and exists even at low active material concentrations.
Conclusions:
- The balance between self-stirring active flows and diffusive fluxes dictates phase separation in active liquid crystals.
- Activity provides a mechanism to control interfacial morphology, leading to new material structures.
- This research offers insights into manipulating interfaces using active components.
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