Continuum percolation of polydisperse rods in quadrupole fields: Theory and simulations

Finner, Shari P.; Kotsev, Mihail I.; Miller, Mark A.; van der Schoot, Paul

Abstract

We investigate percolation in mixtures of nanorods in the presence of external fields that align or disalign the particles with the field axis. Such conditions are found in the formulation and processing of nanocomposites, where the field may be electric, magnetic, or due to elongational flow. Our focus is on the effect of length polydispersity, which—in the absence of a field—is known to produce a percolation threshold that scales with the inverse weight average of the particle length. Using a model of non-interacting spherocylinders in conjunction with connectedness percolation theory, we show that a quadrupolar field always increases the percolation threshold and that the universal scaling with the inverse weight average no longer holds if the field couples to the particle length. Instead, the percolation threshold becomes a function of higher moments of the length distribution, where the order of the relevant moments crucially depends on the strength and type of field applied. The theoretical predictions compare well with the results of our Monte Carlo simulations, which eliminate finite size effects by exploiting the fact that the universal scaling of the wrapping probability function holds even in anisotropic systems. Theory and simulation demonstrate that the percolation threshold of a polydisperse mixture can be lower than that of the individual components, confirming recent work based on a mapping onto a Bethe lattice as well as earlier computer simulations involving dipole fields. Our work shows how the formulation of nanocomposites may be used to compensate for the adverse effects of aligning fields that are inevitable under practical manufacturing conditions.

Citation

Finner, S. P., Kotsev, M. I., Miller, M. A., & van der Schoot, P. (2018). Continuum percolation of polydisperse rods in quadrupole fields: Theory and simulations. The Journal of Chemical Physics, 148(3), Article 034903. https://doi.org/10.1063/1.5010979

• Journal Article Type: Article
• Acceptance Date: Dec 27, 2017
• Online Publication Date: Jan 18, 2018
• Publication Date: Jan 18, 2018
• Deposit Date: Jan 4, 2018
• Publicly Available Date: Jan 10, 2018
• Journal: Journal of Chemical Physics
• Print ISSN: 0021-9606
• Electronic ISSN: 1089-7690
• Publisher: American Institute of Physics
• Peer Reviewed: Peer Reviewed
• Volume: 148
• Issue: 3
• Article Number: 034903
• DOI: https://doi.org/10.1063/1.5010979
• Public URL: https://durham-repository.worktribe.com/output/1337638
• Related Public URLs: https://arxiv.org/abs/1801.00993