Organic–Inorganic Polyimides with POSS Cages in the Main Chains: An Impact of POSS R Groups on Morphologies and Properties

Two well-defined POSS diamines were synthesized with phenyl (Ph) and iso -butyl ( i -Bu) POSS trisilanols as the starting compounds. This approach involves the protection and deprotection of silanol hydroxyl groups with phenylboronic acid and pinacol, followed by the silylation of silanol hydroxyl groups with mono- and dichlorosilanes. With this route of synthesis, two well-defined divinyl POSS macromers were obtained, as evidenced by 1 H, 29 Si NMR, and mass spectroscopy. These two divinyl POSS macromers were further functionalized into well-defined POSS diamines via the Heck reaction with p -bromoaniline. The successful synthesis of POSS diamines enabled the synthesis of organic–inorganic polyimides with the POSS cages in the main chains. More importantly, the syntheses of these two POSS diamines allowed the examination of the effect of POSS R groups ( i.e., Ph and i -Bu) on the morphologies and thermomechanical and dielectric properties of organic–inorganic polyimides. Notably, the types of POSS R groups exerted a profound impact on the morphologies and properties of the organic–inorganic polyimides.