Preparation of poly(ester-imide) ribbons comprised of helical and non-helical blocks by copolymerization

Helical ribbons of poly[4-(5-oxy-1,3-dioxoisoindoline-2-yl)benzoyl] (PODB) were previously prepared by the homo-polymerization of N-(4-carboxyphenyl)-4-acetoxyphthalimide (CAP) in aromatic solvents. The copolymerization of CAP and p-acetoxybenzoic acid (ABA) was examined to change the helical morphology. The helical morphology was extinguished by the copolymerization of a small amount of ABA at 280 °C at a concentration of 1.0% in aromatic solvent. Based on these results, ABA was added stepwise during the homo-polymerization of CAP. When a small amount of ABA was added, copolymer crystals comprised of helical and non-helical blocks were formed. The non-helical blocks grew on the PODB helical ribbons by the precipitation of co-oligomers. This result provides a novel method to control helical morphology by copolymerization.