The reactive oxygen species (ROS)-mediated photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) process is an attractive tool to enhance the oxygen tolerance of radical polymerization systems. In this paper, we investigate the relationship between the covalent organic framework (COF) structure and polymerization performance based on the O 2/H 2 O system by modulating the COF at atomic and molecular levels. We combine density functional theory (DFT) calculations and experiments to clarify the "oxygen-/water-fueled" PET-RAFT polymerization mechanism and identify the key steps of the protocol. Based on the modulation of the TD-1 COF template structure, the relatively efficient charge−hole separation efficiency allows the matching of TD-2 COF and TD-3 COF with the O 2•− /H 2 O system to achieve high-quality RAFT polymerization, providing insights into the rational design and development of catalytic systems with better performance.

Two imine-based covalent organic framework photocatalysts with different building units, TPB-DMTA-COF and TAT-DMTA-COF, for photo-induced energy transfer reversible complexation-mediated radical polymerization (PET-RCMP) were developed and investigated, producing ideal polymers with accurate molecular weight and moderate dispersity under visible light irradiation. The chain extension and spatiotemporal control experiments revealed the high chain-end fidelity of polymers and the compatibility of RCMP processes in both bulk and aqueous system. Moreover, density functional theory (DFT) calculations verified that heteroatom-doped TAT-DMTA-COF exhibits higher activities for weakening CÀ I bond energy barrier, which promotes PET-RCMP polymerization performance. This work demonstrates that rational adjustment of building block for constructing COF heterogeneous photocatalyst can enhance the catalytic performance of PET-RCMP, providing a design methodology for the development of polymeric organic photoelectric semiconductor catalysts to mediate RCMP.

Two imine‐based covalent organic framework photocatalysts with different building units, TPB‐DMTA‐COF and TAT‐DMTA‐COF, for photo‐induced energy transfer reversible complexation‐mediated radical polymerization (PET‐RCMP) were developed and investigated, producing ideal polymers with accurate molecular weight and moderate dispersity under visible light irradiation. The chain extension and spatiotemporal control experiments revealed the high chain‐end fidelity of polymers and the compatibility of RCMP processes in both bulk and aqueous system. Moreover, density functional theory (DFT) calculations verified that heteroatom‐doped TAT‐DMTA‐COF exhibits higher activities for weakening C−I bond energy barrier, which promotes PET‐RCMP polymerization performance. This work demonstrates that rational adjustment of building block for constructing COF heterogeneous photocatalyst can enhance the catalytic performance of PET‐RCMP, providing a design methodology for the development of polymeric organic photoelectric semiconductor catalysts to mediate RCMP.

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The generation of cyclic carbonates by the cycloaddition of CO 2 with epoxides is attractive in the industry, by which CO 2 is efficiently used as C1 source. Herein, a series of catalysts were developed to efficient mediate the cycloaddition of CO 2 with epoxides to generate carbonates. The catalysts were easily synthesized via the amine-formaldehyde condensation of ethidium bromide with a variety of linkers. The newly prepared heterogeneous catalysts have high thermal stability and degradation temperatures. The surface of the catalysts is smooth and spherical in shape. The effect of temperature, pressure, reaction time and catalyst dosage on the cycloaddition of CO 2 with epoxide were investigated. The results show that the catalyst with 1,3,5-tris(4-formylphenyl)benzene as the linker can achieve 97.4 % conversion efficiency at the conditions of 100 °C, reaction time of 12 h, and the reaction pressure of 1.2 MPa in a solvent-free environment. Notably, the polymers serve as homogeneous catalysts during the reaction (reaction temperature above T g ) and can be separated and recovered easily as homogeneous catalysts at room temperature. In addition, the catalyst is not only suitable for a wide range of epoxide substrates, but also can be recycled many times. Furthermore, DFT calculations show that the coordination between the electrophilic center of the catalyst and the epoxide reduces the energy barrier, and the reaction mechanism is proposed based on the reaction kinetic studies and DFT calculations.