An UV and Near-Infrared Dual-Photothermal Responsive Polymer Capable of Red-Light Emission

The integration of long-wavelength red emission and multi-response photothermal properties into a single polymer is highly desired for meeting the requirements of modern functional materials. However, limitations remain in stability and compatibility to unlock the special properties via conventional doping/blending strategies. Herein, by introducing branching structures, the limitations are broken to synergistically integrate and regulate the fluorescence emission and photothermal effects in hyperbranched pyrrole-based polymers (HBPs). The obtained HBPs demonstrate red emission at 650 nm, a large Stokes shift of 219 nm, and intrinsic dual photothermal properties without blending. Of particular note, HBPs rapidly reach 187 °C within 20 s with UV irradiation, and feature sound photothermal conversion stability after four cycles in near-infrared NIR (1.8 W cm⁻²) and UV (0.5 W cm⁻²) irradiation. The practical photothermal conversion performance of HBPs is demonstrated by constructing quickly responsive light-driven actuators via mixing with liquid crystal elastomer. Combined experimental and theoretical calculations reveal that branching generated high-density light-absorption units, cavities, and charge separation induced the ICT effect, which is the dominant mechanism for redshift and photothermal performance. This work provides a promising approach to tailoring fluorescence and integrating fluorescence and photothermal performance, which promotes their applications in multimodality sensors and diagnosis/treatment integration scenarios.