D-Isosorbide (ISB) is an attractive diol candidate for copolyester production because of its biological origin and desirable properties imparted by the resulting polyesters. However, the rigid structure and relatively unreactive hydroxyl groups in ISB can decrease the reactivity (toward glycolysis reactions) of ISB-containing polymers. To confirm the influence of the sterically hindered ISB moiety on the glycolysis of copolyesters, bis(6-hydroxyhexahydrofuro[3,2-b]furan-3-yl) terephthalate (BHDIT), a model compound for poly(isosorbide terephthalate) (PIT), was synthesized. The transesterification reactivity of BHDIT was compared with that of model compounds poly(ethylene terephthalate) (PET) and poly(cyclohexylenedimethylene terephthalate) (PCT). BHDIT exhibited significantly reduced reactivity, with a reaction rate 5 times lower than that of PET. In the glycolysis of copolyesters consisting of PIT, PET, and PCT units, the PIT units exhibited a degradation of only 5% of the PIT units, indicating considerably higher stability than other polymer units. PET glycolysis with ISB, the reverse of PIT glycolysis, exhibited a reduced reaction rate, which was 0.17% of the reaction rate with diethylene glycol. In the glycolysis involving the ISB moiety, the sterically hindered bicyclic ring and secondary alcohol structure of ISB resulted in a decreased transesterification rate that was more than two orders lower than that of PET.

» Author: Linh Nguyet Thi Ho, Dieu Minh Ngo, Jungdong Kim, Hyun Min Jung

» Publication Date: 01/10/2020

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