Polyamide–polyester multiblock copolymers by chain‐coupling reactions of carboxy‐terminated polymers with phenylene and pyridylene bisoxazolines

Polyamide–polyester multiblock copolymers were synthesized through the reaction of α,ω‐dicarboxy polyamides and polyesters with various arylene bis(2‐oxazoline)s. 2,2′‐(2,6‐Pyridylene)bis(2‐oxazoline) was very reactive and yielded multiblock copolymers with number‐average molar masses ranging from 15,000 to 25,000 after 30 min of reaction in the bulk at 200 °C. The molar masses and thermal properties of the resulting random multiblock copolymers (glass‐transition temperature, melting temperature, and melting enthalpy) were close to those of their alternating homologues prepared by conventional polycondensation between diamino polyamides and dicarboxy polyesters. This showed that the presence of coupling agent moieties in the polymer chains did not exert a significant influence on the block copolymer morphology. The chain‐coupling method showed several advantages over conventional polycondensation: a much shorter reaction time, a lower temperature, no byproducts, and easy control of the final copolymer properties through the mass ratio of the starting oligomers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1331–1341, 2005