Self-adaptive and large-area sprayable thermal management coatings for energy saving

Abstract

Self-adaptive thermal management over large areas is highly attractive since single-mode radiative cooling materials lead to undesired overcooling. However, it remains a challenge that dual-mode switchable materials require artificial stimuli or additional energy for switching between heating and cooling modes. Here, different from dual-mode switching materials driven by artificial stimuli or additional energy, we propose an autonomously self-adaptive dual-modal coating with assembled micro-heterostructures that can engender the multistage scattering of incident light. The resultant coating demonstrates 92% solar reflectivity and 93% emissivity in hot condition. More significantly, the coating reaches 60% visible light optical modulation, which is attributed to the formation and disruption of the conjugation region in the chromogenic molecules, to prevent overcooling in cold condition. A thermal-switchable fabric is further fabricated via large-area spraying processes, demonstrating 2.5 °C warmer in cold condition and 8.7 °C cooler in hot condition compared to white samples. The coating highlights the importance of the large-scale manufacturing of temperature-adaptive materials, providing insights into the application of dynamic radiative cooling in garment, camping, building and other fields.