NIR-Light-Induced\nATRP Using Phenothiazine-Based Hollow\nConjugated Microporous Polymer Networks as Photocatalysts for Aerobic\nPhotobiocatalysis

In\norder to fully utilize low-energy near-infrared (NIR) light\nfor photoinduced atom transfer radical polymerization (photo-ATRP),\nit is essential to develop suitable photocatalytic systems capable\nof participating in photoinduced electron transfer processes with\nATRP catalysts, generating activating species. By employing structural\nand morphological engineering techniques, a range of hollow conjugated\nmicroporous polymers (HCMPs) were fabricated by incorporating photoactive\nphenothiazine as the donor unit and various alkyne-terminated linkers\nas acceptor units via the Sonogashira–Hagihara cross-coupling\nreaction on silica templates, followed by removal of the silica inner\ncores. Manipulating the electron affinity of the acceptor units allowed\nfor control over the electron delocalization and exciton binding energy\nof the HCMPs, ultimately enhancing the charge separation efficiency\nand photocatalytic performance for photo-ATRP. Because of the superior\npenetration abilities of NIR wavelengths, photo-ATRP was effectively\nperformed through nontransparent physical and biological barriers,\nshowcasing rapid polymerization rates. This led to the efficient polymerization\nof diverse acrylates and methacrylates with high monomer conversion,\nprecise molecular weight, and narrow dispersity. Notably, this approach\nenabled the synthesis of enzyme–polymer bioconjugates without\nthe need for tedious deoxygenation at NIR wavelengths, rendering them\nideal for highly stable and circular photobiocatalysis in aerobic\nenvironments. The heterogeneous nature of the HCMPs facilitates easy\nseparation and effective reusability in subsequent polymerization\nprocesses.