Electrical Transport in Brownian Dispersions of Conducting Colloidal Particles

Understanding how electrical transport is driven by particle dynamics is required to realize design rules for conductive soft matter. Traditionally, electrical transport in dispersions has been understood to resemble that of percolated nanocomposites, with conductive domains immobilized within a continuous matrix. However, recent evidence suggests a more complex relationship between electrical transport in particle dispersions and the hydrodynamic forces that arise under flow. Herein, we explore how particle diffusion facilitates electrical transport in dispersions prepared using a Newtonian solvent and silver-coated silica spheres. By changing both solvent viscosity and particle volume fraction, we provide new evidence that clarifies the link between electrical transport and dispersion dynamics. To obtain further insight into microscopic dynamics, we parametrized a pair potential and simulated an array of dispersions using Brownian dynamics. Overlaid with Markov chain Monte Carlo simulations, we quantified both the charge fluctuations and the transient clustering dynamics. Through our experimental and computational results, we reveal that the link between long-time particle diffusion and the electrical diffusivity of colloidal particles differs by several orders of magnitude and can be tuned with solvent viscosity.