Swimming to Stability: Structural and Dynamical Control via Active Doping

Abstract

External fields can decidedly alter the free energy landscape of soft materials and can be exploited as a powerful tool for the assembly of targeted nanostructures and colloidal materials. Here, we use computer simulations to demonstrate that nonequilibrium internal fields or forces -- forces that are generated by driven components within a system -- in the form of active particles can precisely modulate the dynamical free energy landscape of a model soft material, a colloidal gel. Embedding a small fraction of active particles within a gel can provide a unique pathway for the dynamically frustrated network to circumvent the kinetic barriers associated with reaching a lower free energy state through thermal fluctuations alone. Moreover, by carefully tuning the active particle properties (the propulsive swim force and persistence length) in comparison to those of the gel, the active particles may induce depletion-like forces between the constituent particles of the gel despite there being no geometric size asymmetry between the particles. These resulting forces can rapidly push the system toward disparate regions of phase space. Intriguingly, the state of the material can be altered by tuning macroscopic transport properties such as the solvent viscosity. Our findings highlight the potential wide-ranging structural and kinetic control facilitated by varying the dynamical properties of a remarkably small fraction of driven particles embedded in a host material.

ACS Nano

References in corpus (30)

• Active Particles in Complex and Crowded Environments
• Motility-Induced Phase Separation
• Athermal Phase Separation of Self-Propelled Particles with no Alignment
• Statistical Mechanics of Interacting Run-and-Tumble Bacteria
• Strong scaling of general-purpose molecular dynamics simulations on GPUs
• Scalar ${\varphi }^4$ field theory for active-particle phase separation
• Pressure and Phase Equilibria in Interacting Active Brownian Spheres
• Observation of empty liquids and equilibrium gels in a colloidal clay
• Activity-induced phase separation and self-assembly in mixtures of active and passive particles
• Freezing and phase separation of self-propelled disks
• Towards a 'Thermodynamics' of Active Matter
• Entropically Patchy Particles: Engineering Valence through Shape Entropy
• Reentrant Phase Behavior in Active Colloids with Attraction
• Generalized Thermodynamics of Phase Equilibria in Scalar Active Matter
• Tunable long range forces mediated by self-propelled colloidal hard spheres
• Stress localization, stiffening and yielding in a model colloidal gel
• An active approach to colloidal self-assembly
• Gelation as arrested phase separation in short-ranged attractive colloid-polymer mixtures
• Casimir Effect in Active Matter Systems
• Diffusion of an ellipsoid in bacterial suspensions
• A novel coarsening mechanism of droplets in immiscible fluid mixtures
• Swim pressure on walls with curves and corners
• Chemical potential in active systems: predicting phase equilibrium from bulk equations of state?
• Crystallizing hard-sphere glasses by doping with active particles
• Curvature-dependent tension and tangential flows at the interface of motility-induced phases
• Tracer diffusion in active suspensions
• Linking particle dynamics to local connectivity in colloidal gels
• Self-assembly of active amphiphilic Janus particles
• Activity-assisted self-assembly of colloidal particles
• Casimir effect in swimmer suspensions

Cited by in corpus (19)

• Microscopic Origins of the Swim Pressure and the Anomalous Surface Tension of Active Matter
• Collective forces in scalar active matter
• Activity-Enhanced Self-Assembly of a Colloidal Kagome Lattice
• Phase Coexistence Implications of Violating Newton's Third Law
• Environmental Memory Boosts Group Formation of Clueless Individuals
• Dynamic Flow Control Through Active Matter Programming Language
• Universal reshaping of arrested colloidal gels via active doping
• Reconfiguration, Interrupted Aging and Enhanced Dynamics of a Colloidal Gel using Photo-Switchable Active Doping
• Active Matter Shepherding and Clustering in Inhomogeneous Environments
• Ostwald-like ripening in the two-dimensional clustering of passive particles induced by swimming bacteria
• Filled Colloidal Gel Rheology: Strengthening, Stiffening, and Tunability
• Kinetic temperature and pressure of an active Tonks gas
• Orbits, spirals, and trapped states: Dynamics of a phoretic Janus particle in a radial concentration gradient
• Dynamic Overlap Concentration Scale of Active Colloids
• Phase Separation, Capillarity, and Odd Surface Flows in Chiral Active Matter
• Theory of Nonequilibrium Multicomponent Coexistence
• Active doping controls the mode of failure in dense colloidal gels
• Transient Pattern Formation in an Active Matter Contact Poisoning Model
• Reinforcement Learning reveals fundamental limits on the mixing of active particles