Facile Synthesis of Gradient Polycarbonate–Polyester Terpolymers from Monomer Mixtures Mediated by an Asymmetric Chromium Complex
Yanchuan Zhou, Zan Gao, Chenyang Hu, Shuaiming Meng, Ranlong Duan, Zhiqiang Sun, Xuan Pang
Abstract
Gradient polycarbonate–polyester copolymers possess distinctive biodegradable and physicochemical properties in comparison with block or random copolymers. However, their synthesis is still a challenge due to the distinct chain-growth mechanisms among various monomers. Herein, we designed a novel asymmetric Cr complex containing a N–H bond of rigid o-aminophenolate moieties. Compared with the typically analogous symmetric salen-Cr(Cl) complex, the well-designed ligand endowed the asymmetric Cr complex with an exceptional ability to synthesize gradient biodegradable terpolymers from monomer mixtures of cyclohexene oxide, CO2, and ε-caprolactone. Specifically, gradient terpolymers were validated by investigating reaction processes and chain microstructures. It should be noted that the configurations of gradient terpolymers could be modulated by adjusting reaction conditions and component ratios, which further influenced the physicochemical properties. The synthetic approach in this work could open avenues to a wide variety of novel gradient copolymers and modify the property of biodegradable materials.