Two-sided comb poly(amic ester)-poly(propylene oxide) graft copolymers as porous polyimide precursors

New step‐growth graft block copolymers were synthesized. These two‐sided comb copolymers consisted of a poly(amic ester) (PAE) backbone and pendant poly(propylene oxide) (PPO) grafts. The copolymers were made via a macromonomer approach, in which the 4,6‐bischlorocarbonyl isophthalic acid bis[poly(propylene oxide)] ester macromonomer was synthesized through the reaction of hydroxyl‐terminated PPO oligomers with pyromellitic dianhydride and oxalyl chloride. This macromonomer was subsequently used in step‐growth polymerization with comonomers 4,6‐bischlorocarbonyl isophthalic acid diethyl ester, 2,5‐bischlorocarbonyl terephthalic acid diethyl ester, and 2,2‐bis[4‐ (4‐aminophenoxy)phenyl] hexafluoropropane, and this yielded PPO‐co‐PAE graft copolymers. Accordingly, we report the synthesis and characterization of the PPO oligomer, the PPO macromonomer, and their corresponding PPO‐co‐PAE graft copolymers. Graft copolymers with PPO concentrations of 3–26 wt % were synthesized. These polymers were thermally cured to produce polyimide/PPO composites. The thermolysis of these polyimide/PPO composites yielded porous polyimide films with porosities ranging of 4–22.5%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2266–2275, 2005 A new type of step‐growth graft block copolymer has been synthesized. These two‐sided comb copolymers consist of a poly(amic ester) backbone with pendant poly(propylene oxide) grafts. The copolymers were made via a macromonomer approach where the 4,6‐bischlorocarbonyl isopthalic acid bis[poly(propylene oxide)] ester macromonomer was synthesized by reacting hydroxyl‐terminated poly(propylene oxide) (PPO) oligomers with pyromellitic dianhydride and oxalyl chloride. This macromonomer was subsequently used in a step‐growth polymerization with comonomers, 4,6‐bis(chlorocarbonyl)‐isopthalic acid diethyl ester (m‐DCDE), 2,5‐bis(chlorocarbonyl)‐terepthalic acid diethyl ester (p‐DCDE), and 2,2‐bis[4‐(4‐aminophenoxy)phenyl] hexafluoropropane (4‐BDAF), to give PPO‐co‐polyamic ester graft copolymers. Accordingly, we report the synthesis and characterization of the PPO oligomer, the PPO macromonomer and their corresponding PPO‐co‐polyamic ester graft copolymers. Graft copolymers with PPO content between 3 and 26 wt % were synthesized. These polymers were thermally cured to give polyimide/PPO composites. Thermolysis of these polyimide/PPO composites yielded porous polyimide films with porosities ranging from 4 to 22.5%.