Visible light-triggered PET-RAFT polymerization by heterogeneous 2D porphyrin-based COF photocatalyst under aqueous condition

Abstract

Covalent organic frameworks (COFs) are promising heterogeneous photocatalytic platforms based on their structural designability and diversity. Here, porphyrin-based TCPP-TPDA-COF was synthesized and served as photocatalyst for the application of oxygen-tolerant photoelectron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization in the aqueous phase under visible light irradiation. The effects of catalyst loading, electron sacrificial agent dosage, solvent type, light sources and target polymerization degrees (DPs) on the polymerization behavior are discussed, and the intrinsic mechanisms of the oxygen tolerance properties are identified by the control experiments and oxygen monitoring experiments. TCPP-TPDA-COF endows the RAFT protocol with efficient light availability, high light dependence, well controllability and compatibility with different families of monomers. Programmable COFs provide a powerful avenue for further expansion of photocatalyst candidates compatible with PET-RAFT processes under oxygenated atmosphere.