A high-molecular-weight and high-Tg poly(ester carbonate) partially based on isosorbide: synthesis and structure–property relationships

Abstract

A new family of high-molecular-weight poly(isosorbide carbonate-co-butylene terephthalate)s (PICBTs) partially based on renewable isosorbide (Is) were prepared by incorporating 1,4-butanediol (BD) and dimethyl terephthalate (DMT) into poly(isosorbide carbonate) (PIC), via a two-step bulk condensation polymerization. The incorporation of BD and DMT was developed to compensate for the low reactivity of Is and improve the molecular weight and processability of PIC, while retaining the rigidity and hence high glass transition temperature (T_g) of PIC. The resulting copolymers showed high number-average molecular weights ranging from 30 600 to 52 300 g mol⁻¹ and tunable T_g values from 69 to 146 °C. The molecular structure of the novel poly(ester carbonate)s was confirmed using ¹H, ¹³C, 2D-COSY and 2D-HSQC NMR techniques. ¹H NMR analysis revealed the random sequence distributions of the PICBTs. A systematic study on the structure–property relationship revealed that the thermal, dynamic mechanical and mechanical properties of the PICBTs strongly depended on their composition, which would enable molecular design of material properties with the desired balance of material rigidity, ductility, and biobased content.