Synthesis of poly(imide-arylene ether phenylquinoxalines)

Abstract

A major drawback in the use of high Tg polyimides in the microelectronics industry is the poor interfacial adhesion for laminated structures, presumably due to the absence of a Tg which prohibits interdiffusion. In an effort to circumvent this, imide-arylene ether phenylquinoxaline statistical copolymers were investigated. A key feature of these copolymers is the incorporation of an arylene ether phenylquinoxaline moiety in the polymer backbone by use of 1,4-[6-(aminophenoxy)-3-phenyl-2-quinoxalinyl] benzene (BAQ) as a diamine in the polyimide synthesis. The synthesis of BAQ was carried out by a nucleophilic aromatic substitution of 1,4-(6-fluoro-3-phenyl-2-quinoxalinyl)benzene with 3-aminophenol in the presence of K2CO3. BAQ was utilized as a comonomer with PMDA and ODA to synthesize the desired poly(amic-acids). Films were cast and cured (350°C) to effect the imidization, affording films with elongations ranging from 60 to 110% with moduli comparable to PMDA - ODA polyimide. The copolymers with high phenylquinoxaline compositions displayed Tg in the 300-320°C range, which is expected to be very important in modifying the adhesion of polyimide. The thermal stability of the copolymers was comparable to that of polyimide with decomposition temperatures in the 470-500°C range.