Synthesis of block copolymers by oligomer‐coupling reactions in the bulk: Bisimidazoline/cooh and bisoxazolinone/nh 2 reactions

The polyaddition reaction of bisimidazolines with α, ω‐dicarboxy polyamide‐12 in the bulk at 200–240°C (oligomer coupling reaction) produces high MW polymers, while degradation reactions were observed with aliphatic polyesters. The chain extension of a α, ω‐dicarboxy polyamide‐polyoxytetramethylene‐polyamide oligomer with 2, 2'‐tetramethylene‐bis(imidazoline) yielded a poly(poly‐ether‐block‐polyamide). 4‐substituted and 4, 4‐disubstituted bis(5(4H)oxazolinones) are efficient coupling agents for amino‐terminated oligomers, allowing the rapid synthesis of copolymers containing polyether and polyamide blocks. The chemistry of these chain‐coupling reactions has been studied by NMR. DSC shows the phase separation between the hard (polyamide) and the soft (polyether) blocks.