Thermochromic hydrogels with an adjustable critical response temperature for temperature monitoring and smart windows

Smart windows have been attracting increasing attention in recent years because of their sunlight modulation and energy management capabilities. However, the response temperature of most of these smart windows is higher than the temperatures that are comfortable for humans, and it is difficult to adjust the response temperature. In this study, a novel thermochromic hydrogel smart window with the capability of reasonable and adjustable response temperature (16-34 degrees C), and excellent transparency (>85%) was developed by introducing sodium dodecyl sulfate (SDS) micelles into crosslinked acrylamide. The thermochromic response property could be finely controlled by changing the amounts of added potassium tartrate (PTH) and polyethylene glycol (PEG). Visible and ultraviolet light could selectively pass through the obtained hydrogel high-temperature environments, while almost all wavelengths of light would be blocked to protect the customers' privacy in low-temperature environments. This design is beneficial for saving energy for illumination and insulation. In addition to being thermo-controlled, the "transparent-opaque" transition of the hydrogel could be actively controlled by regulating the current. The prepared hydrogel-based smart windows present excellent cycling stability and fast and efficient solar modulation characteristics. We also explored the application of the prepared hydrogel in the field of intelligent temperature monitoring and home security protection. The strategy of developing thermochromic hydrogels provides a new approach for next-generation multifunctional energy-saving smart window systems.