Impact of non-reciprocal interactions on colloidal self-assembly with tunable anisotropy

Abstract

Non-reciprocal (NR) effective interactions violating Newton's third law occur in many biological systems, but can also be engineered in synthetic, colloidal systems. Recent research has shown that such NR interactions can have tremendous effects on the overall collective behaviour and pattern formation, but can also influence aggregation processes on the particle scale. Here we focus on the impact of non-reciprocity on the self-assembly of an (originally passive) colloidal system with anisotropic interactions whose character is tunable by external fields. In the absence of non-reciprocity, that is, under equilibrium conditions, the colloids form aggregates with extremely long life times [Kogler et al., Soft Matter 11, 7356 (2015)], indicating kinetic trapping. Here we study, based on Brownian Dynamics (BD) simulations in 2D, a NR version of this model consisting of two species with reciprocal isotropic, but NR anisotropic interactions. We find that NR induces an effective propulsion of particle pairs and small aggregates forming at initial stages of self-assembly, an indication of the NR-induced non-equilibrium. The shape and stability of these initial clusters strongly depends on the degree of anisotropy. At longer times we find, for weak NR interactions, large (even system-spanning) clusters where single particles can escape and enter at the boundaries, in stark contrast to the small rigid aggregates appearing at the same time in the passive case. In this sense, weak NR shortcuts the aggregation. Increasing the degree of NR (and thus, propulsion), we even observe large-scale phase separation if the interactions are weakly anisotropic. In contrast, system with strong NR and anisotropy remain essentially disordered. Overall, NR interactions are shown to destabilize the rigid aggregates interrupting self-assembly in the passive case, helping the system to overcome kinetic barriers.

13 pages, 9 figures, to be published in Journal of Chemical Physics

References in corpus (30)

• Novel type of phase transition in a system of self-driven particles
• Self-motile colloidal particles: from directed propulsion to random walk
• Flocks, herds, and schools: A quantitative theory of flocking
• Dynamical clustering and phase separation in suspensions of self-propelled colloidal particles
• Athermal Phase Separation of Self-Propelled Particles with no Alignment
• Non-reciprocal phase transitions
• Emergent behavior in active colloids
• A continuum theory of phase separation kinetics for active Brownian particles
• Brownian motion of a self-propelled particle
• Self-assembly of catalytically active colloidal molecules: Tailoring activity through surface chemistry
• The Statistical Mechanics of Dynamic Pathways to Self-assembly
• Nonreciprocity as a generic route to traveling states
• Active phase separation in mixtures of chemically interacting particles
• Statistical mechanics for non-reciprocal forces
• Scalar Active Mixtures: The Non-Reciprocal Cahn-Hilliard Model
• Collective Thermotaxis of Thermally Active Colloids
• Non-reciprocity across scales in active mixtures
• Light-controlled Assembly of Active Colloidal Molecules
• Self-assembly of Active Colloidal Molecules with Dynamic Function
• Clustering and flocking of repulsive chiral active particles with non-reciprocal couplings
• Clustering and phase separation of circle swimmers dispersed in a monolayer
• Active Colloidal Molecules
• Pair Interaction of Catalytically Active Colloids: From Assembly to Escape
• Activity-Enhanced Self-Assembly of a Colloidal Kagome Lattice
• Analyzing mechanisms and microscopic reversibility of self-assembly
• Active droploids
• Emerging activity in bilayered dispersions with wake-mediated interactions
• Escaping kinetic traps using non-reciprocal interactions
• Clustering-induced velocity-reversals of active colloids mixed with passive particles
• Phase Coexistence Implications of Violating Newton's Third Law

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