Novel Photothermochromic Smart Window Based on PNIPAm‐glass‐MXene/PAM with High Shield, Fast Response, and Excellent Stability

Abstract

In recent years, smart windows have emerged as an important method to achieve energy efficiency in buildings. The responses of thermochromic smart windows are very dependent on the photothermal absorption of nanoparticles. However, nanoparticles dispersed in thermochromic materials cause high thermal loads on the window's surface and become nonuniform and unstable with time. These problems seriously limit application of photothermochromic smart windows. Herein, a new photothermochromic smart window is designed using bicomponent poly (N‐isopropylacrylamide) PNIPAm and MXene/polyacrylamide (PAM), denoted as P‐g‐M smart window. Compared with other photothermochromic smart windows, the developed P‐g‐M smart window reduces the window's surface temperature, and there is no obvious visibility decrement due to the long‐term stable dispersion of MXene. The small particle size of PNIPAm microgels synthesized by the one‐step method shows high scattering efficiency, and the fabricated 1‐mm PNIPAm displays 91.2% visible light transmittance and 99.2% solar light shielding. While pursuing efficient light management, the P‐g‐M smart window responds 25 min faster than a 1 mm PNIPAm smart window. In addition, the device effectively improves the hydrogel thermal response stability. The indoor and outdoor energy‐saving demonstration shows that P‐g‐M smart windows can reduce indoor air temperature by 5–10 °C compared with normal windows.

Thermochromic Janus Membranes with Dynamic Solar Modulation toward Sustainable and High-Efficiency Solar-to-Thermal Intelligent Management

“…Thermochromic self-responsive smart windows, owing to their simple structure, are more suitable for energy-efficient windows in buildings. Currently, the main thermochromic materials reported include inorganic vanadium dioxide , and some organics such as poly­( N -isopropylacrylamide) (PNIPAM), , poly­( N -vinylcaprolactam), chitosan, hydroxypropylmethylcellulose, polythiophene . Among them, hydrogel based on poly­( N -isopropylacrylamide) PNIPAm has been utilized as a photothermal phase change hydrogel for thermal management applications attributed to its simple preparation and good solar modulation capability .…”

Kirkendall effect induced ultrafine VOOH nanoparticles and their transformation into VO2(M) for energy-efficient smart windows

“…Introduction Building energy consumption accounts for B40% of total global energy consumption, and a major part of this energy (B60%) is lost through windows in the building because of the superabundant solar radiation transmitted through the window increasing the indoor cooling and heating loads for air conditioners in summer and winter, respectively. [1][2][3] Therefore, the use of smart windows that can dynamically regulate the amount of solar transmission in response to an external stimulus could have a significant positive effect on energy savings. Diverse smart windows have been achieved using mechano, thermo, electro, or photo stimuli.…”