Synthesis of Recyclable Polyesters via Catalytic Transfer Hydrogenation–Dehydrogenative Polymerization of Diketones and Diols

Developing recyclable polymers with excellent performance is a cutting-edge direction in polymer science. Herein, we report the direct synthesis of polyesters with branched or ring structures from diketones and primary diols via a “catalytic transfer hydrogenation–dehydrogenative polymerization (CTH-DHP)” cascade reaction catalyzed by a commercially available ruthenium–pincer complex. The thermodynamic properties of the obtained polymers can be precisely controlled by simply adjusting the monomer feed ratios, with a highest melting temperature (Tm) reaching 58.2 °C. This catalytic system displays excellent depolymerization capability and can efficiently depolymerize polyesters under mild conditions into the original primary diols and value-added secondary diols via hydrogenative depolymerization. The recovered diol mixture can be repolymerized into polyesters with the same structure as the original polymers, thereby achieving a closed-loop recycling. This work provides an innovative approach for controlled synthesis and sustainable closed-loop recycling of polyesters.