Scalable Ionogel-Based Thermochromic Smart Windows: Enhanced Solar Regulation, Weatherability, and Processability

Hydrogel-based smart windows suffer from limited weather resistance and processability, while converting thermochromic ionogels into window films suitable for mass production remains a challenge. This paper reports a thermochromic ionogel ink composed of butyl acrylate (BA) and binary ionic liquids (ILs), which has been specifically designed for industrial production to address these bottlenecks. This homogeneous precursor can be rapidly cured by ultraviolet light and is suitable for 3D printing, coating and roll-to-roll curing process, supporting customized pattern design and large-size fabrication. The temperature-driven dynamic distribution of IL-rich microdomains within the polymer matrix endows the material exceptional solar regulation capabilities and tunable low critical solution temperature between 27 and 130 °C. Simultaneously, the as-synthesized film exhibits robust weather resistance, inherent self-adhesiveness, and outstanding thermomechanical stability, effectively preventing liquid leakage, structural degradation, and thermal failure. The outdoor tests and the building energy simulations quantitatively validate its significant energy-saving and emission-reduction effects, highlighting the potential of this ionogel as a durable, energy-efficient platform for next-generation smart windows.