Recent progress of reversible thermochromic hydrogels and their application in smart windows
image: The thermal responsive characteristics of thermochromic hydrogels in smart window applications mainly manifest in the performance regulation of their phase transition temperature, optical properties, structural stability, and response speed.
Credit: Nano Research, Tsinghua University Press
In the context of global energy transition and the urgent pursuit of carbon neutrality, building energy consumption has become a central focus in achieving sustainable development. Although traditional glass windows are widely used, they have limited ability to dynamically regulate indoor thermal environments, often failing to balance energy efficiency with user comfort.
To address this challenge, researchers have turned their attention to thermochromic hydrogel smart windows, a promising class of materials capable of automatically adjusting solar transmittance based on environmental temperature. These smart windows offer a revolutionary solution by enabling "light transmission when cold and light blocking when hot," effectively reducing heating and cooling demands without external power or mechanical control. This dynamic response not only enhances occupant comfort but also significantly contributes to energy savings and environmental sustainability.
Professor Zhan'ao Tan led a research team that recently published a review article titled "Recent progress of reversible thermochromic hydrogels and their application in smart windows" in Nano Research. The article provides an in-depth analysis of the development, performance, and future directions of the thermochromic hydrogel technology for smart windows. The study systematically examines key performance indicators such as phase transition temperature, optical properties, response speed, and cycle stability, while exploring the underlying mechanisms and optimization strategies for material design.
The review highlights several key approaches that have successfully improved the performance of thermochromic hydrogels, including:
- Nanomaterial composites to enhance thermal sensitivity and optical response;
- Microstructural control for precise tuning of phase behavior;
- Crosslinking network optimization to improve mechanical strength and durability.
These strategies have demonstrated significant improvements in temperature adaptability, optical performance, and mechanical robustness, laying a solid foundation for practical applications.
Importantly, the review outlines three strategic research directions for future development:
- Development of wide-temperature-range responsive materials: To enable smart windows to adapt to diverse climatic conditions across different regions and seasons.
- Optimization of low-cost, large-scale manufacturing processes: To overcome challenges in material synthesis and device fabrication, thereby accelerating commercialization.
- Integration of multifunctional capabilities: Exploring synergies with technologies such as photovoltaics and self-cleaning surfaces, to create advanced, intelligent building interfaces.
As global efforts toward energy conservation and climate resilience intensify, thermochromic hydrogel smart windows are poised to play a pivotal role in shaping the future of sustainable construction. With ongoing research and technological advancements, the commercialization of this technology is expected to accelerate, offering a more intelligent and eco-friendly approach to building design.
Other contributors include Lanlan Deng and Xiaodong Xu from Beijing University of Chemical Technology.
This work was supported by the National Natural Science Foundation of China (52373169).
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.