Fully-π conjugated covalent organic frameworks as catalyst for photo-induced atom transfer radical polymerization with ppm-level copper concentration under LED irradiation

Abstract

Photo-induced atom transfer radical polymerization (ATRP) becomes a significant method for preparing well-defined polymers with pre-designable molecular weight and narrow molecular weight dispersity (Mw/Mn). Herein, a fully-π covalent organic framework (COF) was constructed and served as heterogeneous photocatalyst for photo-induced ATRP under LED irradiation. TCPB-DMTA-COF, which was constructed by Knoevenagel polycondensation of 1,3,5-tris(4-cynomethylphenyl)benzene (TCPB) and 2, 5-Dimethoxy-terephthalaldehyde (DMTA) and exhibited remarkable performance in mediating photo-induced ATRP of methyl methacrylates with the assist of ppm-level concentration of CuII under LED irradiation, producing polymers with high chain-fidelity and low value of Mw/Mn (1.10–1.35). The switch “on/off” experiment exhibits excellent temporal and spatial control toward polymerization system. Compared with TCPB-DMTA-CMP, the high crystallinity and stability of TCPB-DMTA-COF endows high monomer conversion and good recyclability performance for photo-induced ATRP. These results suggest COF can be served as a promising artificial photocatalyst for photo-induced ATRP.