**Abstract**

Polymer nanocomposite-based dielectric materials are playing a vital role in the area of electrical insulation research and developments. The nanoparticle dispersion and interface region are the crucial parts of these developments. This chapter begins with the description of physical properties and their derived nanoparticles of polyimide (PI) films. Then, the detailed synthesis process of PI/nanocomposite multilayer film and its optimization is discussed in this chapter. Several factors in the synthesis process, which can influence the quality of the film, are discussed. After synthesis, the dielectric properties such as space charge were measured, and the results are compared with single and multilayer PI/nanocomposite films. Simulations and modeling help to shed light on the experimental results and create an understanding of polymer nanocomposite properties. Therefore, the PI/ nanocomposite multilayer 3D model based on boundary conditions obtained from SEM/TEM images of synthesized samples was also constructed and simulated in COMSOL multiphysics software. The nanoparticle agglomeration and the impact of nanoparticle dispersion on the electrical properties of the material are described in detail in this model. The results demonstrate that the nanoparticle dispersion is improved by using a thin layer of PI/nanocomposite on PI film. As a result, fewer space charges and low electric fields are observed in multilayer films.

**Keywords:** polyimide nanocomposite, multilayer insulation, synthesis optimization, dielectric properties, polyimide nanocomposite modeling
