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

High crystallinity of fully sp2 COF, TCPB-DMTA-COFs , was constructed and served as heterogeneous photocatalyst for inducing atom transfer radical polymerization with the assist of ppm-level of Copper as co-catalyst under LED light irradiation, producing polymers with narrow molecular weight dispersity and highly chain-end fidelity. [Display omitted] • Fully-π conjugated covalent organic framework, TCPB-DMTA-COF , was successfully designed and synthesized. • TCPB-DMTA-COF was served as photocatalyst to mediate photo-induced ATRP with the assist of ppm-level copper under LED irradiation, producing polymers with uniform molecular weight and narrow molecular weight dispersity. • The switch on/off experiments and chain extension reaction proved the high chain-end fidelity of the obtained polymers and temporal control of polymerization processes. • Comparing with TCPB-DMTA-CMP , TCPB-DMTA-COF with high crystallinity presented better catalytic properties during polymerization, providing that the crystallization of COF strongly improves its catalytic polymerization. • Mechanism study of polymerization processes by EPR experiments reveal the formation of radical. 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 (M w / M n). 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 M w / M n (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. [ABSTRACT FROM AUTHOR]