Monte Carlo simulation of cylinders with short-range attractions

Abstract

Cylindrical or rod-like particles are promising materials for the applications of fillers in nanocomposite materials and additives to control rheological properties of colloidal suspensions. Recent advances in particle synthesis allows for cylinders to be manufactured with short-ranged attractions to study the gelation as a function of packing fraction, aspect ratio and attraction strength. In order to aid in the analysis of small-angle scattering experiments of rod-like particles, computer simulation methods were used to model these particles with specialized Monte Carlo algorithms and tabular superquadric potentials. The attractive interaction between neighboring rods increases with the amount of locally-accessible surface area, thus leading to patchy-like interactions. We characterize the clustering and percolation of cylinders as the attractive interaction increases from the homogenous fluid at relatively low attraction strength, for a variety of aspect ratios and packing fractions. Comparisons with the experimental scattering results are also presented, which are in agreement.

Tabular Potentials for Monte Carlo Simulation of Supertoroids with Short-Range Interactions

“…The following anisotropic model is similar to that described in Ref. [10]. In particular, the shapes are modeled as hard particles with short-range attractions given by an implicit depletant potential.…”

“…where r h is the hard contact distance, which is a function of orientation and is computed numerically [10]. This numerical calculation utilizes a grid of surface points, as described in Ref.…”

“…Due to the development of new techniques for nanoparticle construction [1][2][3][4][5], recent years have seen rapid growth in the use of anisotropic colloids [6,7]. Colloids have become an appealing base for self-assembly studies because the interaction, both attractive and repulsive, between particles can be controlled by manipulating the properties of the individual particles, such as the particle anisotropy [8][9][10][11]. This push for the development of more exotic types of colloids has caused an increased demand for simulations that accurately and efficiently predict the system behavior over a range of thermodynamic conditions.…”

“…This push for the development of more exotic types of colloids has caused an increased demand for simulations that accurately and efficiently predict the system behavior over a range of thermodynamic conditions. Many studies have presented models that describe the behavior of systems of convex, solid particles [10,[12][13][14]. Expansion of the model to include porous, concave [15][16][17][18] shapes would allow the examination of systems relevant for drug delivery [17,[19][20][21], optics [17,19], catalysis [22], and photonics [20,21].…”

“…This work outlines a modification to the methodology presented in Ref. [10], which was previously used to create tabular potentials for simulation of superquadrics, so that the method is now also capable of simulating supertoroids.…”