Thermochromic Smart Windows with Ultra-High Solar Modulation and Ultra-Fast Responsive Speed Based on Solid-Liquid
Guangjun Zhu1,2, Gang Xu2,3, Yu Zhang4
1State Key Laboratory of High Performance Civil Engineering Materials, Southeast University, Nanjing 211189, China.
Research (Washington, D.C.)
|August 7, 2025
Summary
A novel solid-liquid switchable thermochromic hydrogel offers rapid response and structural integrity for advanced smart windows. This innovation significantly reduces energy consumption and CO2 emissions in buildings.
Area of Science:
- Materials Science
- Polymer Science
- Sustainable Energy
Background:
- Thermo-responsive hydrogels are crucial for smart windows in energy-efficient buildings.
- Existing hydrogels suffer from slow response times and structural degradation.
Purpose of the Study:
- To develop a durable, fast-responding thermo-responsive hydrogel for smart windows.
- To address the limitations of current smart window materials.
Main Methods:
- Synthesized a solid-liquid switchable thermochromic hydrogel (SL-PNIPAm) using dynamic imine bonds.
- Cross-linked Poly(N-isopropylacrylamide) (PNIPAm) with AMEO.
- Encapsulated SL-PNIPAm in glass panels to create smart windows.
Main Results:
- SL-PNIPAm exhibited rapid response (within 5 s) and maintained structural integrity without shrinkage.
- Smart windows achieved high luminous transmittance (96.8%) and solar modulation (89.7%).
- Simulated experiments showed a 22 °C indoor temperature reduction and a 54% decrease in HVAC energy consumption.
Conclusions:
- The developed hydrogel system offers superior durability for smart windows.
- This technology promotes the advancement and retrofitting of thermochromic smart windows.
- Significant reductions in building energy consumption and CO2 emissions are achievable.
Related Concept Videos
01:16Specific Heat
The specific heat capacity of a substance refers to the energy required to increase the temperature of one gram of that substance by one degree Celcius. Specific heat capacity is often represented in calories (cal), grams (g), and degrees Celsius (oC), but can also be expressed in joules (J), kilograms (kg), and Kelvin (K), among other units.
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or 4186 J/kg/K.
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or 4186 J/kg/K.
02:04Regulation of Transpiration by Stomata
During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.
01:57Adaptations that Reduce Water Loss
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
01:11P-N junction
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...