Ultra-low electrical conductivity originated from ordered and tightly aggregated interfacial regions in polymer nanocomposites

The utilization of renewable energy requires power capacitors to maintain low electrical conductivity and high energy storage performance, and it is urgent to develop excellent electrical insulating polymer nanocomposites (PNCs). The improved electrical insulating performance of PNCs originates from the interfacial regions with low conductivity. However, the scale and mesoscopic electrical conduction properties of interfacial regions lack quantitative research. We convert the above questions into an inversion problem of solving the generalized Poisson equation. The Monte Carlo method is used to construct the structure model, and we simulate the distributions of electric fields and the effective electrical conductivity of PNCs via a high-throughput method. Comparing the simulation results and experiments, we obtain that for the polyimide/γ-Al2O3, polyimide/HfO2, and crosslinked divinyltetramethyldisiloxane-bis(benzocyclobutene)/γ-Al2O3 PNCs, the maximum thicknesses of interfacial regions can reach 8.2, 6.0, and 2.7 times of the radii of nanofillers respectively, and their conductivities can be up to 934.6, 613.5, and 60.0 times lower than those of polymer matrices, respectively. It is concluded that the ordered and tightly aggregated structure in PNCs induced by the bound effect of nanofillers on molecular chains is the formation mechanism of interfacial regions with low conductivity.