Two‐in‐One Strategy for Photoinduced Atom Transfer Radical Polymerization Using Cu(I)‐Phenothiazine Integrated Covalent Organic Frameworks

The concurrent development of innovative photocatalysts (PCs) that achieve fast reaction rates while ensuring efficient catalyst recycling remains a significant challenge for large-scale polymer production. Herein, we present a "two-in-one" strategy that combines a photoactive component with a cyclic trinuclear Cu(I)-incorporated triangular complex as the intrinsic copper source within three imine-linked covalent organic frameworks (COFs). As-synthesized photoactive Cu(I)-containing COFs demonstrated exceptional performance in aqueous photoinduced atom transfer radical polymerization (photo-ATRP), achieving a record-breaking turnover number (TON) of 1640 and turnover frequency (TOF) of 82 min^-1, while maintaining narrow polymer dispersity of 1.20. Such performance surpasses previously reported heterogeneous PCs designed for photo-ATRP. Notably, the COF-encapsulated "two-in-one" catalytic design endows the system with remarkable operational stability and near-quantitative catalyst recovery. More importantly, such new COFs demonstrate outstanding process compatibility, enabling scalable production of well-defined block copolymers in a single microreactor, without intermediate purification.