Synthesis of poly(ethylene terephthalate-co-isophthalate) via ring-opening polymerization of their cyclic oligomers

Abstract

Syntheses of poly(ethylene terephthalate-co-isophthalate) (PET-co-PEI) were achieved via ring-opening copolymerization of corresponding cyclic oligoesters. The ring-opening polymerization (ROP)-PET-co-PEI were prepared by equilibrating an equimolar amount of cyclic oligo(ethylene terephthalate) and cyclic oligo(ethylene isophthalate) using di-n-butyltin oxide catalyst under high concentration conditions at 270 and 290 °C for 8 and 12 h. The copolyesters were obtained in yields of up to 91% with the inherent viscosity (ηinh) of up to 2.89 dl/g indicating the drastically high molecular weight compared with the conventional and ROP routes for the synthesis of PEI. The differential scanning calorimetry data of ROP-PET-co-PEI showed the melting temperatures above 400 °C indicated the potential used in high temperature application.