Effects of rigid or adaptive confinement on colloidal self-assembly. Fixed vs. fluctuating number of confined particles

Abstract

The effects of confinement on colloidal self-assembly in the case of fixed number of confined particles are studied in the one dimensional lattice model solved exactly in the Grand Canonical Ensemble (GCE) in [J. Pȩkalski et al. J. Chem. Phys. 142, 014903 (2015)]. The model considers a pair interaction defined by a short-range attraction plus a longer-range repulsion. We consider thermodynamic states corresponding to self-assembly into clusters. Both, fixed and adaptive boundaries are studied. For fixed boundaries, there are particular states in which, for equal average densities, the number of clusters in the GCE is larger than in the Canonical Ensemble.The dependence of pressure on density has a different form when the system size changes with fixed number of particles and when the number of particles changes with fixed size of the system. In the former case the pressure has a nonmonotonic dependence on the system size. The anomalous increase of pressure for expanding system is accompanied by formation of a larger number of smaller clusters. In the case of elastic confining surfaces we observe a bistability, i.e. two significantly different system sizes occur with almost the same probability. The mechanism of the bistability in the closed system is different to that of the case of permeable walls, where the two equilibrium system sizes correspond to a different number of particles.

The influence of confinement on the structure of colloidal systems with competing interactions

“…Similar studies have been performed for two dimensional system and spherical cavities. [18][19][20][21][22][23][24][25][26] The computer simulations have been performed for a lattice model 25,26 and a model with continuous potential. 18,19 Apart from simulations these systems have been studied within the density functional theory.…”

Orientational ordering of lamellar structures on closed surfaces

“…The used ratio matches the ratio of the repulsion to attraction strengths studied in the lattice model in Refs. [17,18,28,29,53]. The same form of the SALR potential was previously studied in Refs.…”

“…decreasing the wall separation has an effect analogous to decreasing the temperature [26]. The geometry, permeability and elasticity of the confinement, however, play an important role for the ordering of inhomogenous SALR structures [15,[27][28][29].…”

Structural and Dynamical Behaviour of Colloids with Competing Interactions Confined in Slit Pores

“…Surprisingly, the study of confinement in simple geometries, such as a slit pore, has not been sufficiently explored. Indeed we are only aware of a few studies in which fluids with competing interactions confined between parallel plates were studied, but those were restricted to two-and one-dimensional cases [20,28,29]. The literature on the dynamic behaviour of fluids with competing interactions in confinement is also scarce [30].…”