Multifunctional phase change film with high recyclability, adjustable thermal responsiveness, and intrinsic self-healing ability for thermal energy storage

Phase change materials (PCMs) present promising potential for guaranteeing safety in thermal management systems. However, most reported PCMs have a single application in energy storage for thermal management systems, which does not meet the growing demand for multi-functional materials. In this paper, the flexible material and hydrogen-bonding function are innovatively combined to design and prepare a novel multi-functional flexible phase change film (PPL). The 0.2PPL-2 film exhibits solid-solid phase change behavior with energy storage density of 131.8 J/g at the transition temperature of 42.1 °C, thermal cycling stability (500 cycles), wide-temperature range flexibility (0–60 °C) and self-healing property. Notably, the PPL film can be recycled up to 98.5% by intrinsic remodeling. Moreover, the PPL film can be tailored to the desired colors and configurations and can be cleverly assembled on several thermal management systems at ambient temperature through its flexibility combined with shape-memory properties. More interestingly, the transmittance of PPL will be altered when the ambient temperature changes (60 °C), conveying a clear thermal signal. Finally, the thermal energy storage performance of the PPL film is successfully tested by human thermotherapy and electronic device temperature control experiments. The proposed functional integration strategy provides innovative ideas to design PCMs for multifunctionality, and makes significant contributions in green chemistry, high-efficiency thermal management, and energy sustainability.