Design of Persistent and Stable Porous Radical Polymers by Electronical 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 electronical 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 prevent them from recombination. The resulting porous radical polymer exhibits exceptional radical characters with ultralow bandgap 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 oC and striking solar-driven water evaporation efficiency of 96.8%. Our results demonstrate the feasibility of electronical isolation of radicals for producing outstanding photothermal materials.