Ligand regulation strategy of COF-based photocatalyst for ROS-mediated RAFT polymerization

Abstract

The covalent organic framework (COF) has been investigated as an ideal platform for heterogeneous photocatalysis, as it can integrate large π-conjugated systems and customize ligand structure to adjust electron distribution and efficiently promote photoelectric conversion. Herein, TAPT-DMTA-COF and TAPT-DMTA/TP-COF were designed and investigated as metal-free reactive oxygen species (ROS) generators to facilitate generation of ROS clusters to initiate reversible addition–fragmentation chain transfer (RAFT) polymerization (ROS-RAFT) in open vessels under aqueous conditions, yielding polymers with acceptable molecular weights and narrow values for dispersity. Chain-extension and light-control experiments demonstrated the high chain-end fidelity of the polymers and the light-dependent features of the polymerization process. Electron donor group (–OMe)-modulated TAPT-DMTA/TP-COF can efficiently improve the ability of TAPT-TP-COF to produce ROS and accelerate ROS-RAFT polymerization. This work provides a new method for constructing ROS-RAFT polymerization photocatalysts by adjusting the ligand structure of the COF, and establishes a controlled polymerization methodology for expanding the applications of RAFT polymerization.