Controlled Solid-State Ring-Opening Polymerization of Cyclic Carbonates via Mechanochemical H-Bonding Organocatalysis

Mechanochemical tools offer a sustainable route to solid-state polymerization via unique force-activated mechanisms. However, achieving well-controlled living mechanochemical polymerization has remained a challenge. In this study, we proposed a mechanochemical hydrogen-bond-catalyzed ring-opening polymerization (mechano-HROP) strategy that enabled efficient and controllable solid-state polymerization of cyclic carbonates at room temperature. Mechanical force lowers the activation energy of the ROP, while hydrogen bonding further reduces the energy barrier and governs the polymerization process. As a result, solid-state mechano-HROP exhibited exceptional polymerization reactivity (k_obs 29 °C = 0.0137 min^-1). Kinetics analysis confirmed a controlled/living process, and DFT calculations supported a hydrogen-bonded bifunctional activation mechanism in the solid state. This method successfully yielded a series of functionalized aliphatic polycarbonates (M_n up to 178.9 kDa, D̵ < 1.18) with complete monomer conversion and a high storage modulus of 1.75 GPa. The resulting polymers exhibited high end-group fidelity and potential for chain extension and copolymerization. Overall, this study underscored the significance of mechanochemical hydrogen-bond catalysis for sustainable polymer synthesis.