Sunlight-Triggered Phase Change Energy Storage Composite Materials for Human Body Thermal Management

In order to maintain thermal comfort in the human body, photothermal conversion and energy storage microcapsules were designed, developed, and applied in a light-assisted thermoregulatory system. The octyl stearate as a phase change material (PCM) was encapsulated using a polytrimethylolpropane triacrylate (PTMPTA)/polyaniline (PANI) composite as the shell, which was synthesized by adding the intermediate half oxidation state of PANI into the polymerization system of trimethylolpropane triacrylate (TMPTA). In the PCM microcapsules, the PANI particles embedded in the shell can convert sunlight into heat energy to feed the PCM core for energy storage, further realizing the temperature regulation and solving the problem that the phase change behavior cannot be triggered in cold environments. The octyl stearate@PTMPTA/PANI microcapsules exhibit a latent heat of over 103 J/g, good thermal reliability, and 89.12% photothermal conversion efficiency (PCM microcapsules (MEPCM) suspension). Owing to the excellent photothermal performance of the PANI, the thermal energy will be generated under sunshine and simultaneously transferred to the microcapsules for energy storage. As a result, the MEPCM-PTMPTA/PANI can not only achieve a higher temperature than ambient air but also initiate the phase transition process. The obtained microcapsules were further printed on a T-shirt, and a test of self-thermoregulation was carried out in winter. The results suggest that MEPCM-PTMPTA/PANI has good photothermal conversion and temperature regulation capacity under sunshine and low temperature environments.