High-transmittance pNIPAm gel smart windows with lower response temperature and stronger solar regulation

Abstract

Improving the solar regulation and reducing the response temperature of thermochromic smart windows are pivotal importance for energy-saving buildings. However, such two strategies are challenging to be integrated into one window. Herein, a solution for simultaneously regulating the surface tension of the scattering center and the capturing-releasing capacity of pNIPAm for water is implemented, successfully carrying out the enhancement of solar regulation and the reduction of response temperature. The maximum solar shielding and regulation of the modified sandwich structured pNIPAm gel device can reach up to 88.45% and 71.81%, an increase of 52.29% and 73.71% respectively, compared to a pure pNIPAm gel device with the same thickness. Besides, the response temperature is reduced to around 28 ℃, making modified devices have the ability to respond promptly at the comfortable room temperature range boundary (22–28 ℃). Different from flowing, strengthless modified doped microgels, the high-transmittance modified pNIPAm gels maintain the stable patterning performance, and have great potential for further applications. Similar conclusions are obtained using different solvents to reduce the attraction between pNIPAm-water, and the surface tension of water. Therefore, this universal modification framework deserves attention for the future design of energy-saving windows.