Synthesis and characterization of novel hyperbranched polyimides based on silsesquioxane nanocomposite networks

A series of nanosized polyimides was successfully prepared by condensation polymerization of an octaamino-functionalized silsesquioxane and a series of commercially available dianhyride monomers. The polymerization of the octaamino silsesquioxane was carried out in 1-methyl-2-pyrrolidone (NMP) at room temperature, giving poly(amic acid) as precursor polymers that were readily converted to the corresponding polyimides by thermal treatment in the subsequent step, which is similar to the conventional 2-stage method. The appropriate molar ratio of the Silsesquioxane monomer to a dianhyride was 1:1. These polyimides are readily soluble in polar aprotic solvents such as 1-methyl-2-pyrrolidone, and N, N-dimethylacetamide at room temperature, and show high thermal stability with a 10% weight loss, $T_d$ = 441 to 593 °C in N2.