Active interaction switching controls the dynamic heterogeneity of soft colloidal dispersions

Abstract

We employ Reactive Dynamical Density Functional Theory (R-DDFT) and Reactive Brownian Dynamics (R-BD) simulations to investigate the dynamics of a suspension of active soft Gaussian colloids with binary interaction switching, i.e., a one-component colloidal system in which every particle stochastically switches at predefined rates between two interaction states with different mobility. Using R-DDFT we extend a theory previously developed to access the dynamics of inhomogeneous liquids to study the influence of the switching activity on the self and distinct part of the Van Hove function in bulk solution, and determine the corresponding mean squared displacement of the switching particles. Our results demonstrate that, even though the average diffusion coefficient is not affected by the switching activity, it significantly modifies the non-equilibrium dynamics and diffusion coefficients of the individual particles, leading to a crossover from short to long times, with a regime for intermediate times showing anomalous diffusion. In addition, the self-part of the van Hove function has a Gaussian form at short and long times, but becomes non-Gaussian at intermediates ones, having a crossover between short and large displacements. The corresponding self-intermediate scattering function shows the two-step relaxation patters typically observed in soft materials with heterogeneous dynamics such as glasses and gels. We also introduce a phenomenological Continuous Time Random Walk (CTRW) theory to understand the heterogeneous diffusion of this system. R-DDFT results are in excellent agreement with R-BD simulations and the analytical predictions of CTRW theory, thus confirming that R-DDFT constitutes a powerful method to investigate not only the structure and phase behavior, but also the dynamical properties of non-equilibrium active switching colloidal suspensions.

15 pages, 7 figures

References in corpus (9)

• Anomalous transport in the crowded world of biological cells
• Universal nature of particle displacements close to glass and jamming transitions
• "Diffusing diffusivity": A model for anomalous and "anomalous yet Brownian" diffusion
• Self-diffusion and Interdiffusion in Al80Ni20 Melts: Simulation and Experiment
• Clustering and heterogeneous dynamics in a kinetic Monte-Carlo model of self-propelled hard disks
• Non-universal tracer diffusion in crowded media of non-inert obstacles
• The van Hove distribution function for Brownian hard spheres: dynamical test particle theory and computer simulations for bulk dynamics
• Controlling the microstructure and phase behavior of confined soft colloids by active interaction switching
• Relaxation dynamics in a transient network fluid with competing gel and glass phases

Cited by in corpus (11)

• Intermittent Attractive Interactions Lead to Microphase Separation in Non-motile Active Matter
• Perspective: New directions in dynamical density functional theory
• Motion of an active particle with dynamical disorder
• Derivation and analysis of a phase field crystal model for a mixture of active and passive particles
• Hot Brownian Motion of thermoresponsive microgels in optical tweezers shows discontinuous volume phase transition and bistability
• Transmission of mobility via cooperative mechanisms in soft active matter
• Dynamic phase transition induced by active molecules simulating a facilitation mechanism in a supercooled liquid
• Metadensity functional learning for classical fluids: Regularizing with pair correlations
• Active responsive colloids driven by intrinsic dichotomous noise
• Controlling the Glass Transition through Active Fluctuating Interactions
• A facilitation-induced fluidization transition in supercooled water triggered by a few active molecules