Biomimetic Dyeable Photothermal Aerogel Fibers with Passive Insulation and Active Photothermal Capacity for Thermoregulating Clothes

Photothermal aerogel fibers offer promise for intelligent thermal management in extreme cold environments, yet their scalable production is hindered by slow gelation kinetics, poor mechanical strength, and limited dyeability. Herein, we report an in situ photo-cross-linking strategy for the fast gelling fabrication of dyeable photothermal aerogel fibers, using thermoplastic polyurethane (TPU) as the sheath and methacrylated chitosan (CSMA) aerogel as the core. The photosensitive CSMA core cross-links within 15 s under UV irradiation, enabling fast sol–gel transition in a deionized-water coagulation bath within 1 min. The trade-off between dyeability and photothermal performance is addressed by incorporating cesium tungsten bronze (CWO) nanoparticles into the TPU sheath layer or in situ polymerizing polypyrrole (PPy) in the CSMA core layer, whereby light-blue TPU/CWO@CSMA fibers and near-white TPU@CSMA-PPy fibers were developed. Both fibers exhibit excellent mechanical properties (tensile strength 3.1–3.3 MPa, elongation >1600%) and low thermal conductivity (0.047 ± 0.0004 W·m–1·K–1), achieving a good synergistic optimization of passive thermal insulation and active photothermal heating performance. They also display good dyeability for multicolored fabrication while maintaining strong photothermal performance. TPU/CWO@CSMA fibers heat to 66.7 °C under 1-sun illumination and reach 19.2 °C at −20 °C via CWO’s LSPR effect. TPU@CSMA-PPy fibers show mild, controllable warming (≈16 °C at −7 °C; 20 °C at 0 °C) with slower cooling. Outdoor tests confirm fabric temperatures remain in a mild 25–34 °C range without overheating. This work overcomes the long-standing technical bottleneck of conventional photothermal aerogel fibers that are typically restricted to single, undyeable colors, demonstrating promising potential for personal thermal management and related applications.