Barrier properties of k-mer packings

TL;DR

This study uses Monte Carlo simulations to analyze how arrangements of k-mers on a lattice affect their ability to block diffusion, revealing that certain loose packings can be more effective barriers than dense ones.

Contribution

It provides new insights into the barrier properties of k-mer packings, especially in loose arrangements, and discusses discrepancies with existing effective medium theory predictions.

Findings

Loose RSA and RD packings show percolation-like diffusion behavior.

Large k-mers can form more effective barriers than dense packings.

Simulation results differ from effective medium theory predictions.

Abstract

This work discusses numerical studies of the barrier properties of k-mer packings by Monte Carlo method. The studied variants of regular and non-regular arrangements on a square lattice included models of random sequential adsorption (RSA) and random deposition (RD). The discrete problem of diffusion through the bonds of a square lattice was considered. The k-mers were perfectly oriented perpendicular to the diffusion direction and blocked certain fraction of bonds $f_b$ against diffusion. For loose RSA and RD packings, the percolation like-behavior of diffusion coefficient was observed and the data evidenced that their barrier properties at large values of k may be more effective than those of some dense packings. Such anomalous behavior can reflect the details of k-mer spatial organization (aggregation) and structure of pores in RD and RSA packings. The contradictions between simulation data and predictions of EM theory were also discussed.