Dual-functional polyimide-based phase change composite aerogels with latent heat storage and radiative cooling capabilities for energy-efficient buildings

Abstract To enhance the building’s indoor temperature regulation capability and reduce the energy consumption of the building, a series of functional composite materials with solar-thermal conversion and storage capabilities as well as radiative cooling capabilities have been developed. In this work, we report the development of a dual-functional polyimide (PI)-based phase change composite material that simultaneously possesses latent heat storage and radiative cooling capabilities. First, carbonized PI fibers (CPIF) were prepared via electrospinning. The CPIF dispersion was mixed with polyamic acid aqueous solution, and then CPIF/PI aerogels (CPs) were manufactured through the process of freeze-drying and thermal imidization. The CPs were placed into molten polyethylene glycol (PEG) to obtain CPIF/PI phase change materials (CPPCMs) via the process of vacuum impregnation, and finally, a boron nitride (BN) coating was applied to the surface to acquire the shape-stable BN@CPPCMs. CPIF improves the thermal conductivity of BN@CPPCMs and enhances sample stability through its compatibility with PI. Meanwhile, the BN coating can increase the solar reflectivity of BN@CPPCMs, significantly reducing their temperature during operation. This dual-functional composite material can prevent single radiative coolers from suffering thermal accumulation and high-temperature damage, integrating latent heat storage and radiative cooling, achieving high enthalpy efficiency and effective temperature regulation for energy-efficient buildings.