Closed-Loop green precipitation polymerization for kinetically controlled multifunctional polymer microspheres

Multifunctional polymer microspheres are indispensable in catalysis, separation, and drug delivery, yet their scalable fabrication is often hampered by low solvent recovery, narrow synthetic scope, and poor kinetic control. These limitations not only lead to solvent wastage and environmental burdens, but also cause undesirable outcomes such as uncontrolled polymerization and broadened particle size distributions. Herein, we report a green, sustainable, and kinetically controllable precipitation polymerization strategy that couples rotary evaporation with a closed-loop solvent management system. This platform enables the efficient synthesis of polymer microspheres bearing diverse functional groups, thereby broadening their applicability across multiple application scenarios. The process achieves a solvent recovery rate of up to 95.2%, affords precise regulation of crosslinking density (0.05–0.80), and simultaneously improves both monodispersity and yield (up to 68.7% at high crosslinking degrees). Notably, the recovered acetonitrile can be directly reused without additional purification, underscoring the robustness of the solvent recycling scheme. Overall, this scalable approach integrates kinetic control, functional versatility, and solvent circularity into a unified process, providing a practical route to high-quality multifunctional polymer microspheres while minimizing solvent waste and obviating complex post-treatment steps.