Lamellar to Micellar Phases and Beyond: When Tactic Active Systems Admit Free Energy Functionals
1Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France.
Physical Review Letters
|December 1, 2020
Summary
Active particles exhibiting taxis can exhibit equilibrium behaviors, similar to Brownian colloids. This study reveals how taxis can lead to phase separation and collapse in active matter systems.
Area of Science:
- Statistical Mechanics
- Soft Matter Physics
- Active Matter
Background:
- Active particles exhibit complex dynamics distinct from passive systems.
- Taxis, or directed motion in response to a field, is a key behavior in active matter.
- Understanding phase transitions in active systems is crucial for their applications.
Purpose of the Study:
- To establish a connection between microscopic models of tactic active particles and equilibrium statistical mechanics.
- To explain the emergence of lamellar and micellar phases in active systems.
- To investigate phase separation phenomena driven by chemotaxis.
Main Methods:
- Development of microscopic models for active particles with field-dependent properties.
- Derivation of fluctuating hydrodynamics for tactic active systems.
- Mapping active systems to equilibrium models of interacting Brownian colloids.
Main Results:
- A broad class of tactic active systems can be described by hydrodynamics equivalent to equilibrium systems.
- Taxis can directly lead to the formation of lamellar and micellar phases observed in soft colloids.
- Chemotaxis, involving chemoattractants and repellents, can induce liquid-gas phase separation and chemotactic collapse.
Conclusions:
- Active and passive systems can share fundamental hydrodynamic descriptions under certain conditions.
- Taxis is a significant factor driving emergent collective behaviors and phase transitions in active matter.
- Chemotaxis can result in genuine equilibrium phase separation, challenging traditional views of active matter dynamics.
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