Enhancing Aqueous Reversible Addition–Fragmentation Chain Transfer Photopolymerization in Continuous Flow Reactors with Hairy Hollow Conjugated Microporous Polymer Nanocomposites

Abstract

Continuous flow polymerizations have emerged as a reliable and sustainable approach for polymer production and processing, promoting efficient and uniform irradiation pathways. However, the hurdles posed by existing photocatalysts, including restricted photocatalytic efficiency and stability, poor solvent dispersibility, and intricate separation and purification processes, continue to hinder the progress of aqueous photopolymerization in a flow reactor. This study focuses on the strategic design and synthesis of hairy hollow conjugated microporous polymer nanocomposites (S-hEBDT-P HCMPs) through Sonogashira–Hagihara coupling on SiO2 templates, succeeded by sulfonation, polymer grafting, and subsequent elimination of the SiO2 cores. Due to their high aqueous dispersibility and exceptional oxygen tolerance, these S-hEBDT-P materials serve as heterogeneous catalysts for initiating aqueous photopolymerization in both batch and continuous flow systems at accelerated rates. Through the optimization of chemical concentrations and reaction rate, the continuous flow systems achieve maximum polymer yields and low dispersities (Đ ∼ 1.08) to scale up polymer production. The catalyst-bound nanocomposites could be conveniently separated and reused via straightforward centrifugation, exhibiting minimal leaching and sustained catalytic performance through multiple polymerization cycles. This represents a pioneering instance of a metal-free heterogeneous nanocatalyst capable of attaining accelerated polymerization kinetics and generating well-structured polymers for continuous flow polymerization in an aqueous environment without deoxygenation.