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