Design of Persistent and Stable Porous Radical Polymers by Electronic Isolation Strategy

Conjugated organic radical polymers with stable radical features are difficult to design because the π conjugation in the polymer backbones makes the radicals readily delocalize and tend to undergo covalent bonding processes. In this work, we report an electronic isolation strategy to design stable porous radical polymers by homocoupling reaction from a meta-position active monomer. The meta linkage ensures less conjugation in the polymer skeletons, localizes the resonant radicals, and prevents them from recombination. The resulting porous radical polymer exhibits exceptional radical characters with ultralow band gap of 0.68 eV, strong yet extended UV/Vis-NIR absorption up to 1800 nm, and high spin density. The above features make the polymer very promising in the photothermal conversion with record-high photothermal temperature increment of ≈∼240 °C and striking solar-driven water evaporation efficiency of 96.8 %. Our results demonstrate the feasibility of electronic isolation of radicals for producing outstanding photothermal materials.