Hybrid thermochromic hydrogels based on HPC/PVA for smart windows with enhanced solar modulation

Energy-saving smart windows could reduce building energy consumption by dynamically regulating solar transmission without consuming additional energy. However, current thermochromic smart windows based on hydroxypropyl cellulose (HPC) are still facing challenges, such as low durability and unsatisfactory in regulating the solar infrared region. To expand hydrogels' modulation ability of infrared region, hydrogels with temperature-sensitive properties of polyvinyl alcohol (PVA) and HPC were prepared and applied in thermochromic smart windows areal. The HPC-PVA hydrogels have an ultra-high luminous transmission in the visible light rather than infrared light regions, blocking most of the sunlight when the temperature increases, thus greatly enhancing the solar modulating ability (∆ T sol ) and infrared transmittance modulation (∆ T IR ). The 4 wt.% PVA doped in HPC exhibits the best solar modulation ability (∆ T IR, (20–50 °C) 5.5%, Δ T sol, (20–50 °C) 19.4% and T lum, 20 °C 91.3%). In addition, these high-performance and temperature-sensitive materials have a high repetition and durability. The hydrogels could obtain adjusting broadband sunlight smart windows with sandwich structure glasses. Graphic abstract Hybrid thermochromic hydrogels HPC-PVA were designed by one-step hydrothermal method categories. The hydrogels could increase the temperature-responsive of smart hydrogels, enhance solar modulation and have high luminous transmission.