Synthesis of Thermal-Resistant Polyester-Polycarbonate with Fully Rigid Structure from Biobased Isosorbide

Developing green and sustainable polymers is one of the effective ways to limit carbon emissions and reduce dependence on petroleum resources. Therefore, polyester-polycarbonates based on carbon dioxide (CO2) have attracted extensive attention. However, polyester-polycarbonates with fully rigid structures are difficult to prepare by traditional transesterification methods, which result in low glass transition temperatures and insufficient mechanical properties. Here, a series of polyester-polycarbonates (PCCITs) with a fully rigid structure were prepared by end hydroxyl shielding using dimethyl carbonate derived from CO2 and biologically sourced isosorbide (IS), and the IS content is 0–60 mol %. The ester bond structure of polyester-polycarbonate was analyzed by two-dimensional correlation spectroscopy (2DCOS). Due to the V-shaped fused ring structure of IS, the heat resistance of the copolyester is significantly improved. The glass transition temperature of PCCITs ranges from 64.2 to 131.1 °C, and its heat distortion temperature can reach up to 120.1 °C. Furthermore, all copolyesters are entirely amorphous and exhibit good transparency (>88%) and low haze value (<4%). Notably, the mechanical properties of PCCITs are comparable to those of commercial heat-resistant polyethylene terephthalate glycol (PETG), with the tensile strength of PCCT to PCCIT60 increasing from 43.5 to 57.8 MPa, elongation at break ranging from 206.0 to 4.5%, and impact strength up to 820.3 J m–1. Life cycle assessment evaluation showed that the GWP value of PCCIT was significantly reduced, up to 41.5%, compared with commercial PETG. This work constructs sustainable IS-based polyester-polycarbonate with fully rigid through the terminal hydroxyl shielding method.