NIR-Light-Induced ATRP Using Phenothiazine-Based Hollow Conjugated Microporous Polymer Networks as Photocatalysts for Aerobic Photobiocatalysis

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