A Multiscale Characterization of Nanodielectrics: the Case of PI/Si3N4 Nanocomposite

Nanodielectrics are extensively investigated due to their improved properties attributed to the interphase formed between the nanoparticle and the matrix. The objective of this paper is to perform a multiscale characterization on polyimide (PI) / silicon nitride (Si3N4) nanocomposite (NC) in order to determine the impact of the interphase on macroscale properties. NC with untreated and silane treated particles are compared. On the macroscale, breakdown strength and conductivity measurements are performed. On the nanoscale, the interphase thickness and the charge injection and decay are measured using modes derived from the Atomic Force Microscopy (AFM). Results show a higher conductivity of the interphase area compared to the matrix and a direct link between local and macroscopic properties. In addition, the interphase region, with a lower permittivity than the matrix, may present a local enhancement of the applied electric field, leading to a lower breakdown strength for NC materials.