Structure and dynamics of amphiphilic Janus spheres and spherocylinders under shear

Abstract

We study the structure formation and flow properties of colloidal dispersions comprised of Janus spheres, Janus spherocylinders, and their mixtures, using hybrid molecular dynamics simulations that take into account hydrodynamic interactions.

Janus Particles at Fluid Interfaces: Stability and Interfacial Rheology

“…Not only the Janus character and amphiphilicity of the particle affect the rheological properties of the interfacially-trapped particle monolayer, but an applied shear flow itself is shown to impact the configuration of particles and their assembly, yielding interesting structural motifs, which, in turn, can be used to tune the rheological properties (i.e., shear viscosity). Studies have been carried out for assembly both at fluid interfaces and in bulk [259][260][261][262][263]; we will focus on the former here. Using a multicomponent Lattice-Boltzmann method, Rezvantalab et al studied the directed assembly of a cluster of randomly oriented spherical Janus particles into ordered structures at a sheared interface between two immiscible fluids, schematically shown in Figure 7e [258].…”

Diffusion and sedimentation in colloidal suspensions using multiparticle collision dynamics with a discrete particle model

“…In this concentration regime, the functional form of the hydrodynamic interactions remains unchanged, 64 but the interactions must propagate through a medium with an effectively higher viscosity. 42,65,66 Hence, finite-concentration effects can be accounted for in Eq. ( 11) by replacing the solvent viscosity η 0 by the suspension viscosity η.…”

“…[39][40][41] Unlike in reflection-based coupling schemes, the colloid is fully penetrable to the solvent, and the vertex particles couple to the solvent only during the stochastic collision. In addition to the benefits of addressing physical and computational challenges associated with reflection-based coupling, this model is compatible with arbitrary colloid shapes such as spherocylinders 42 and with complex surface patterns. 42,43 The hydrodynamic properties of a single such colloid were studied for various degrees of discretization, finding good agreement with low-Reynoldsnumber theoretical predictions when one vertex particle occupied approximately one collision cell.…”

“…In addition to the benefits of addressing physical and computational challenges associated with reflection-based coupling, this model is compatible with arbitrary colloid shapes such as spherocylinders 42 and with complex surface patterns. 42,43 The hydrodynamic properties of a single such colloid were studied for various degrees of discretization, finding good agreement with low-Reynoldsnumber theoretical predictions when one vertex particle occupied approximately one collision cell. 38 To our knowledge, however, the properties of suspensions represented using this colloid model in MPCD have not been studied in detail.…”

Asymmetric Assembly of Lennard-Jones Janus Dimers

“…MD studies of JPs can typically be categorised into those which model Janus particles as single 'atoms' using point potentials [17,20,22,46] or those which represent spherical JPs as collections of atoms distributed over the sphere's surface (Fig. 1(a)) [47][48][49][50][51]. A manyatom JP is important for the study of hydrodynamic effects such as the effect of slip on particle rotation and translation [51][52][53][54].…”