Simulation of Field-Induced Rheology and Conductivity in Nanorod Polymer Nanocomposites

Abstract

Polymer nanocomposites embedded with polarizable nanoparticles offer promising opportunities for designing smart materials with field-switchable macroscopic properties. In this study, we employ coarse-grained Langevin dynamics simulations to investigate the effect of direct current electric fields on the structural, dynamic, electrical, and rheological responses of a polymer matrix doped with nanorods (NRs). We track the electro-orientation of the NRs under cyclic stimulation, evaluate the resulting electrical conductivity, and compute the composite’s macroscopic shear viscosity. Our simulations reveal a distinct structural hierarchy based on field intensity: low fields induce individual NR alignment, whereas higher amplitudes drive the self-assembly of NRs into filaments that eventually merge into bundles. Using a resistor network model, we demonstrate that this microstructure dictates the material’s performance, yielding an enhancement around four orders of magnitude in electrical conductivity for small field increments in excellent agreement with theoretical predictions. Furthermore, we investigate the system’s rheological thickening response under applied shear flow, revealing a 15-fold increase in viscosity along specific anisotropic directions for the strongest field, a behavior that aligns well with established scaling laws once the microstructure emerges.