Synthesis of Random, Gradient, and Block-like Terpolycarbonates via One-Pot Terpolymerization of Epoxide, CO2, and Six-Membered Cyclic Carbonates

Multi-polymerization is regarded as a valuable strategy to tailor material performances by incorporating well-chosen monomers and tuning monomer sequence distributions in the polymer backbones. Despite that considerable advances have been made in the past decades, the modification of CO2-based polycarbonate materials is still in its infancy. In this contribution, a series of polycarbonate terpolymers with diverse chain structures were fabricated through a dissymmetric Cr complex-catalyzed one-pot terpolymerization of cyclohexene oxide (CHO), CO2 with six-membered cyclic carbonates (6CCs). The reaction conditions (temperature, feeding ratio, and CO2 pressure) as well as the 6CC substituents played a critical role in tailoring the sequence distributions of CHO/CO2/6CC terpolymers from random to gradient or block-like sequences. It was noteworthy that the average lengths of both sequences could be modulated by adjusting the feeding monomer ratios or reaction temperature, as detected by quantitative 13C NMR spectroscopy of purified terpolymers. Besides, DSC revealed that the glass-transition temperature of the obtained terpolymers had a wide range of 69.5-115.5 degrees C based on the polymer architecture.