Self-propelled particles include both self-phoretic synthetic colloids and various micro-organisms. By continually consuming energy, they bypass the laws of equilibrium thermodynamics. These enforce Boltzmann distribution in thermal equilibrium: steady state is then independent kinetic parameters. In contrast, self-propelled tend to accumulate where move more slowly. They may also slow down at high density, for either biochemical or steric reasons. This creates positive feedback which can...

We attribute similarities in the rheology of many soft materials (foams, emulsions, slurries, etc.) to shared features structural disorder and metastability. A generic model for mesoscopic dynamics ``soft glassy matter'' is introduced, with interactions represented by a mean-field noise temperature x. find power law fluid behavior either (x<1) or without (1<x<2) yield stress. For 1<x<2, both storage loss modulus vary frequency as $\omega^{x-1}$, becoming flat near glass transition (x=1)....

We consider materials whose mechanical integrity is the result of a jamming process. argue that such media are generically ``fragile,'' unable to support certain types incremental loading without plastic rearrangement. Fragility linked marginal stability force chain networks within material. It can lead novel responses may be relevant (a) jammed colloids and (b) poured sand. The crossover from fragile elastoplastic behavior explored.

We consider self-propelled particles undergoing run-and-tumble dynamics (as exhibited by E. coli) in one dimension. Building on previous analyses at drift-diffusion level for the one-particle density, we add both interactions and noise, enabling discussion of domain formation ``self-trapping,'' other collective phenomena. Mapping onto detailed-balance systems is possible certain cases.

Experiments, theory, and simulation were used to study glass formation in a simple model system composed of hard spheres with short-range attraction (“sticky spheres”). The experiments, using well-characterized colloids, revealed reentrant transition line. Mode-coupling theory calculations molecular dynamics simulations suggest that the reentrance is due existence two qualitatively different glassy states: one dominated by repulsion (with structural arrest caging) other bonding). This...

Active matter systems are driven out of thermal equilibrium by a lack generalized Stokes-Einstein relation between injection and dissipation energy at the microscopic scale. We consider such system interacting particles, propelled persistent noises, show that, small but finite persistence time, their dynamics still satisfy time-reversal symmetry. To do so, we compute perturbatively steady-state measure for short times, entropy production rate vanishes. This endows with an effective...

Colloidal particles or nanoparticles, with equal affinity for two fluids, are known to adsorb irreversibly the fluid-fluid interface. We present large-scale computer simulations of demixing a binary solvent containing such particles. The newly formed interface sequesters colloidal particles; as coarsens, forced into close contact by interfacial tension. Coarsening is dramatically curtailed, and jammed layer seemingly enters glassy state, creating multiply connected, solid-like film in three...

The problem of stress relaxation in entangled, reversibly breakable polymers (e.g., wormlike micelles) is considered. In the case where dominant diffusive mode for reptation, this has been treated earlier numerical work by coupling full reaction kinetics scissions and recombinations to dynamics reptation (represented a one-dimensional stochastic process). Here we study simplified renewal model, which replaces exact Poisson jump process that neglects temporal correlations chain length...

Certain viscoelastic surfactant solutions show unusual nonlinear rheology: In steady shear, the shear stress saturates to a constant value while first normal stess increases roughly linearly with rate over several decades. Here we explain this behavior in terms of ``reptation-reaction'' model for dynamics reversibly breakable, polymerlike micelles. The constitutive equation leads flow instability shear-banding type. limiting is predicted be...

We study the statistics of a grafted polymer brush, consisting set monodisperse chains in solution, each attached irreversibly by one end to flat surface. use self-consistent field method, valid limit weak excluded volume and at moderately high surface coverage. Exploiting fact that are highly stretched, we map problem (in long-chain limit) onto involving motion classical particles an equal-time potential, which can solve exactly. The resulting density profile for brush takes parabolic form.

Active Brownian particles (ABPs), when subject to purely repulsive interactions, are known undergo activity-induced phase separation broadly resembling an equilibrium (attraction-induced) gas-liquid coexistence. Here we present accurate continuum theory for the dynamics of phase-separating ABPs, derived by direct coarse-graining, capturing leading-order density gradient terms alongside effective bulk free energy. Such do not obey detailed balance; yet find coarsening closely that separation....

Practical and theoretical considerations that apply when aiming to formulate by ultrasonication very small nanoemulsions (particle diameter up 150 nm) with high stability are presented discussed. The droplet size evolution during sonication can be described a monoexponential function of the time, characteristic time scale depending essentially on applied power. A unique master curve is obtained plotting mean as energy. We then show Ostwald ripening remains main destabilization mechanism...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of polydispersity in the end-grafted polymer brushS. T. Milner, A. Witten, and M. E. CatesCite this: Macromolecules 1989, 22, 2, 853–861Publication Date (Print):February 1, 1989Publication History Published online1 May 2002Published inissue 1 February 1989https://doi.org/10.1021/ma00192a057RIGHTS & PERMISSIONSArticle Views1490Altmetric-Citations293LEARN ABOUT THESE METRICSArticle Views are COUNTER-compliant sum full text article downloads...

Recently, there has been much interest in activity-induced phase separations concentrated suspensions of "active Brownian particles" (ABPs), self-propelled spherical particles whose direction motion relaxes through thermal rotational diffusion. To date, almost all these studies have restricted to 2 dimensions. In this work we study separation 3D and compare the results with previous new 2D simulations. end, performed state-of-the-art dynamics simulations up 40 million ABPs -- such very large...

We derive a microscopic expression for the mechanical pressure P in system of spherical active Brownian particles at density ρ. Our exact result relates P, defined as force per unit area on bounding wall, to bulk correlation functions evaluated far away from wall. It shows that (i) P(ρ) is state function, independent particle-wall interaction; (ii) interactions contribute two terms one encoding slow-down drives motility-induced phase separation, and other direct contribution well known...

We investigate the phase behavior and kinetics of a monodisperse mixture active (i.e., self-propelled) passive isometric Brownian particles through dynamics simulations theory. As in purely system, motility component triggers separation into dense dilute phase; phase, we further find active-passive segregation, with ``rafts'' ``sea'' particles. that from an initially disordered can occur as little 15% being active. Finally, show system prepared suitable fully segregated initial state...

Adding a non-adsorbing polymer to passive colloids induces an attraction between the particles via `depletion' mechanism. High enough concentrations lead phase separation. We combine experiments, theory and simulations demonstrate that using active (such as motile bacteria) dramatically changes physics of such mixtures. First, significantly stronger inter-particle is needed cause Secondly, finite size aggregates formed at lower show unidirectional rotation. These micro-rotors self assembly...

We explore a generic mechanism whereby droplet of active matter acquires motility by the spontaneous breakdown discrete symmetry. The model we study offers simple representation “cell extract” comprising, e.g., actomyosin solution. (Such extracts are used experimentally to cytoskeleton). Actomyosin is an gel whose polarity describes mean sense alignment actin fibres. In absence polymerization and depolymerization processes (‘treadmilling’), gel’s dynamics arises solely from contractile...

Active matter systems, composed of individual agents that use energy to self-propel, operate far from thermal equilibrium. But markers nonequilibrium at macroscopic scales are often elusive. A new theoretical analysis shows how diagnose large-scale breakdowns in time-reversal symmetry, which is a key property nonequilibrium.

We study the statistical properties of active Ornstein-Uhlenbeck particles (AOUPs). In this simplest models, Gaussian white noise overdamped Brownian colloids is replaced by a colored noise. This suffices to grant system hallmark matter, while still allowing for analytical progress. in detail steady-state distribution AOUPs small persistence time limit and spatially varying activity. At collective level, we show experience motility-induced phase separation both presence pairwise forces or...