One-pot construction of random, gradient and triblock copolymers from CO2, epoxides and phthalic anhydride by metal-free catalyst.

Random and gradient terpolymers are successfully synthesized by one-pot copolymerization of epoxides/ethylene oxide (EO)/CO 2 and phthalic anhydride (PA)/EO/CO 2 via triethylborane (TEB)-activated catalysis, respectively. The random terpolymer of cyclohexene oxide (CHO)/EO/CO 2 exhibits one glass transition temperature (T g), which can be adjusted in the range of 26–126 °C by simply varying CHO content. The PA/EO/CO 2 terpolymers are proved to be gradient structure and show two separated T g s. To synthesize polycarbonate-type triblock copolymers, a tandem strategy is employed to copolymerize CHO/CO 2 for preparing poly(cyclohexene carbonate) (PCHC) as di-functional macroinitiator first, and then trigger the EO/CO 2 copolymerization to afford poly(ethylene carbonate) (PEC) as two external blocks. A series of high-molecular-weight PEC-PCHC-PEC triblock copolymers are obtained with phase separation microstructures (M n = 126–275 kg mol⁻¹). All obtained copolymers are characterized by ¹H NMR, diffusion-ordered spectroscopy (DOSY), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Thermogravimetric analysis (TG) and mechanical test show that the obtained terpolymers exhibit superior and tailorable performances compared with PEC. [Display omitted] • Synthesis of high-molecular-weight EO/CO 2 -based copolymers catalyzed by metal-free catalyst at the first time. • The mechanical and thermal performances of EO/CO 2 copolymer were improved by the introduction of rigid CHO or PA. • PCHC-PEC-PCHC triblock copolymers were synthesized via tandem strategy. [ABSTRACT FROM AUTHOR]