Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

Abstract

The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large selfpropelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of chains were observed for low and high grafting densities. Surprisingly, we found a weak descent of the end-to-end distance of chains for high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath.

Beating of grafted chains induced by active Brownian particles

“…Figure 3(b) shows that the horizontal inhomogeneity of particle distribution initially grows rapidly with propelling force and then gradually approaches a plateau. In contrast, the Gini coefficient of the horizontal distribution of ABPs in the 3D brush system 31 is small and almost independent of the propelling force, suggesting homogeneous horizontal distribution of ABPs (Fig. S1 in the Supporting Information).…”

“…As expected, with the increase of propelling force, more and more ABPs accumulate in the brush region, the same as our observation in the 3D system. 24 On the one hand, excluded-volume interactions between particles and chains tend to keep the particles outside the brush region. On the other hand, the grafted chains lower the mobility of trapped ABPs, and hence cause the accumulation of particles in the brush region (enhanced self-trapping mechanism).…”

“…Our previous work has focused on the statistical behavior of brush deformation and active particle penetration in three dimensions (3D). 24 In this work, we study the interplay between brush-coated surface and ABPs in two dimensions (2D), which may happen in confined geometry, e.g. thin film or liquid-liquid interface.…”

An Active Approach to Colloidal Self-Assembly

“…This is an area of research that has received considerable interest and a number of analytical, numerical, and experimental results have been published on the subject [12,[66][67][68][69][70][71][72][73][74][75]. In fact, it has been shown that active fluids not only can generate a pressure on a boundary, but they can also induce exotic (depletion-like) effective forces between passive particles (tracers) with range and strength controlled by l p , that can be orders of magnitude larger than what expected for passive systems [73,[76][77][78][79][80][81][82][83][84]. These results suggest ways of designing microstructures to perform specific tasks when immersed in an active suspension.…”

Globule–stretch transition of a self-attracting chain in the repulsive active particle bath

“…As a special case, polymer chains act as a deformable and movable boundary. The cooperation between the passive thermal motion of chain beads and the active non-thermal motion of particles leads to anomalous static and collective dynamic behaviors of the chains/active particles assembly [19][20][21][22][23].…”