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-C4H90）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.

Thermodynamics of Aromatic Cyclic Ester Polymerization in Bulk

We present here the thermodynamic investigation of in situ cascade polycondensation-coupling ring-opening polymerization(PROP)for three cyclic aromatic ester monomers,i.e.,cyclic oligo(2-methyl-1,3-propylene terephthalate)s(COMPTs),cyclic oligo(neopentylene terephthalate)s(CONTs)and cyclic oligo(2-methyl-2-propyl-1,3-propylene terephthalate)s(COMPPTs).The equibrium monomer to polymer weight ratio in bulk at different polymerization temperatures for each monomer was estimated by the size exclusion chromatography(SEC),and the thermodynamic parameters were estimated by Dainton equation.Quite different from the thermodynamics of aliphatic lactones polymerization,which is an exothermic process with entropy reduction,our results showed the polymerization thermodynamics for three cyclic aromatic ester monomers was a weak exothermic process with slight entropy increment,i.e.,a both enthalpy and entropy driving process.Among them,CONTs showed the largest value of enthalpy change,due to its symmetric dimethyl substitution onβ-position of propandiol segments.