Synthesis of cyclic oligo(ethylene adipate)s and their melt polymerization to poly(ethylene adipate)

We present here the first synthesis of cyclic oligo(ethylene adipate)s (COEAs) via pseudo-high dilution condensation reaction of adipoyl chloride with ethylene glycol,and the synthesis of corresponding poly(ethylene adipate) (PEA) via the melt polymerization of COEAs.The structure of COEAs was characterized and proved by 1H-NMR and MALDI-TOF mass measurements.The effects of organic base,reaction temperature and the ratio of adipoyl chloride to ethylene glycol on the yield of COEAs were studied,and the optimum reaction condition was revealed.PEA,a diacid and diol based semi-crystalline green aliphatic polyester,was synthesized by the melt polymerization of COEAs using Ti(n-C4H9O)4 as catalyst and 1,10-decanediol as initiator at 200 ℃,which follows the polycondensation-coupling ring-opening polymerization method.Our strategy should be applicable to the synthesis of versatile aliphatic polyesters based on diacid and diol monomers,which have potential applications as biocompatible and biodegradable materials.