Polyamic alkyl esters: versatile polyimide precursors for improved dielectric coatings

Several approaches leading to high-solids-content polyimide precursor formulations and polyimides with multiphase morphologies have been successfully explored. These approaches were made possible by utilizing poly(amic alkyl esters), which are soluble polyimide precursors devoid of hydrolytic instability and which can be designed to imidize at significantly higher temperatures than their poly(amic acid) counterparts. The hydrolytic stability of these derivatives provides great synthetic flexibility due to solubility considerations, polymer work-up procedures, and polymer modification schemes. The synthetic flexibility is complemented by higher imidization temperatures, which provide the necessary processing window to permit the use of a condensation-chemistry-based, linear chain-extension scheme. In addition, higher imidization temperatures may further advantageously influence the development of well-defined microphase-separated morphologies in the case of block copolymers and polyimide blends