Cubic silsesquioxane-polyimide nanocomposites with improved thermomechanical and dielectric properties

Two series of nanoporous polyimide nanocomposites with well-defined tether architecture have been prepared from octa(aminophenyl)silsesquioxane. Transmission electron microscopy, solid-state 29Si nuclear magnetic resonance, model reaction, and density measurement show that the nanostructures of the polyimide nanocomposites are well defined and can be adjusted accordingly. The polyimide nanocomposites exhibit tunable dielectric constant with a lowest value of 2.29. The thermomechanical properties of the polyimide have been improved significantly with the addition of octa(aminophenyl)silsesquioxane; for instance, glass transition temperature increases by ~80 °C and storage modulus by 46%, as compared to the neat polyimide. Moreover, thermal stability, coefficient of thermal expansion, hardness, and moisture absorption of the polyimide nanocomposites are also improved significantly.