Explore the vast range of titles available.

Thermochromic smart windows technology can intelligently regulate indoor solar radiation by changing indoor light transmittance in response to thermal stimulation, thus reducing energy consumption of the building. In recent years, with the development of new energy-saving materials and the combination with practical technology, energy-saving smart windows technology has received more and more attention from scientific research. Based on the summary of thermochromic smart windows by Yi Long research groups, this review described the applications of thermal responsive organic materials in smart windows, including poly(N-isopropylacrylamide) (PNIPAm) hydrogels, hydroxypropyl cellulose (HPC) hydrogels, ionic liquids and liquid crystals. Besides, the mechanism of various organic materials and the properties of functional materials were also introduced. Finally, opportunities and challenges relating to thermochromic smart windows and prospects for future development are discussed.

Stimuli‐responsive polymers have found applications as shape‐memory materials, optical switches, and sensors, but the installation of these responsive properties in non‐polar and inert polyolefins is challenging. In this contribution, a series of spiropyran (SP)‐based comonomers are synthesized and copolymerized with ethylene or ethylene/cyclic monomers. In addition to great mechanical and surface properties, these functionalized polyolefins responded to light, heat, and force, which induced changes in the polymer structure to transmit color or mechanical signals. These interesting responsive properties are also installed in a series of commercial polyolefin materials through reactive extrusion, making the scalable production of these materials possible. A spiropyran (SP)‐based polyolefin is shown here, which can simultaneously achieve exciting functions such as mechanochromism, photochromism, thermochromism, shape memory, and so on. More importantly, these interesting responsive properties are also installed in a series of commercial polyolefin materials through reactive extrusion, making the scalable production of these materials possible.

An irreversible thermochromic material based on manganese violet (MnNH4P2O7) is synthesized. The crystal phase, chemical composition, and morphology of the synthesized material are analyzed using X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, and Fourier-transform infrared spectroscopy. The absorption spectra of the synthesized material are obtained using a UV-Vis spectrometer, and the thermochromism exhibited by the powdered samples at high temperatures is also investigated. The as-synthesized manganese violet pigment consists of pure α-MnNH4P2O7 phase. In addition, the synthesized pigment largely consists of hexagonal crystals with a diameter of hundreds of nanometers. On heating, the pigment simultaneously loses H2O and NH3 in two successive steps at approximately 330–434.4 °C and 434.4–527 °C, which correspond to the formation of an intermediate phase and of Mn2P4O12, respectively. An overall mass loss of 14.22% is observed, which is consistent with the expected 13.79%. An irreversible color change from violet to white is observed after exposure of the synthesized manganese violet pigment at 400 °C for 30 min. This is attributed to the oxidation of ammonia to hydroxylamine, which then decomposes to nitrogen and water, or alternatively to the direct oxidation of ammonia to nitrogen. Furthermore, we demonstrate the potential application of synthesized manganese violet in the production of irreversible thermochromic paint by mixing with potassium silicate solution as a binder and deionized water as a solvent at a specific ratio. The thermochromic paint is then applied in fabrication of irreversible thermochromic sensors by coating it onto a steel plate surface. Finally, we show that manganese violet-based irreversible thermochromic sensors are able to detect temperatures around 400 °C by changing color from violet to white/milky.

Extreme weather and massive energy demands in facility agriculture threaten food security. However, the current optical switching strategy fails to provide adequate crop climate management, since creating thermochromic materials capable of reversible and temperature‐bidirectional optical modulation across a wide temperature range remains a formidable challenge. Here, a nanocolloid system comprising two tailored thermoresponsive copolymers that achieve optical‐thermal regulation by a temperature‐bidirectional phase transition is reported. Adopting the cononsolvency in a binary solvent, the nanocolloid exhibits a widely tunable transition from 27–85 °C (heat‐induced) and −9–36 °C (cold‐induced). In the transparent state, the nanocolloid‐based smart window achieves a high photosynthetically active radiation (PAR) transmittance (>91%). Upon heating, it shows remarkable solar modulation ability ( ΔT sol up to 65.43%), while upon cooling, it provides a high PAR diffuse reflectance of 27.92% and enhances supplemental lighting efficiency by 33.91%. As a proof of concept in climate‐resilient agriculture, nanocolloid‐based smart windows reduce energy consumption by 11.61 kJ·m −3 (cooling) and 2.96 kJ·m −3 (heating), while boosting photosynthetic rates of specific crops by 222.19% and 126.07% under heat and cold stress, respectively. The bidirectional optical‐thermal regulation by nanocolloid‐based smart windows enables low‐energy agriculture through higher light use efficiency, thereby reducing the carbon footprint in sustainable agriculture.

Vanadium dioxide (VO2) is a well-known phase-changing material that goes from a semiconducting state to a metallic one at a critical temperature of 68 °C, which is the closest to room temperature (25 °C). The electrical transition is also accompanied by structural and optical changes. The optical transition upon heating-also known as thermochromism-makes VO2 a possible coating for “intelligent” windows. In this work, the relationship between the thermochromic performance of VO2 films and the surface morphology was investigated using Temperature-dependent Atomic Force Microscopy (T-AFM) in conjunction with the X-ray Diffraction technique and Scanning Electron Microscopy. In particular, VO2 films were deposited using the rf sputtering technique on Silicon and glass substrates at a substrate temperature of 300 °C, which is one of the lowest for this technique to grow the thermochromic monoclinic phase of VO2. It was found that upon heating (25–100 °C), there was a decrease in RMS roughness for all films independent from the substrate; the value of RMS roughness, however, varied depending on the substrate. Finally, the thermochromic parameters of the VO2 films were correlated with the surface morphology and appeared to be dependent on the kind of substrate used.

Using Cunninghamia lanceolata as a substrate, the thermochromic ink was added to the waterborne finish to test the optical properties and mechanical properties of the finish film. The results showed that the discoloration performance of the finish film with 15.0% and 30.0% of the thermochromic ink was better. The gloss of the finish film changes irregularly when the concentration increases. The finish film with a thermochromic ink concentration of 10.0% has the highest gloss, and with a concentration of 30.0% has the lowest gloss. When the thermochromic ink concentration exceeds 15.0%, the impact resistance of the finish film is slightly enhanced. The concentration is not related to the liquid resistance of the finish film. When the thermochromic ink concentration was 0–15.0%, the particle distribution uniform reunion was not much. The discoloration mechanism of discolored finish film can be considered to be as follows. After adding thermochromic ink, when the finish film temperature rises, it fades from red to colorless. When the temperature is lowered, the thermochromic ink changes to its original colour again, and the thermochromic effect is stable and sustainable. On the basis of the above results, when the thermochromic ink concentration is 15.0%, the general performance of the waterborne finish film on the Cunninghamia lanceolata surface is the best. This study provides new prospects in using thermochromic ink for waterborne finish film.

Significance Artificial systems that replicate functional attributes of the skins of cephalopods could offer capabilities in visual appearance modulation with potential utility in consumer, industrial, and military applications. Here we demonstrate a complete set of materials, components, fabrication approaches, integration schemes, bioinspired designs, and coordinated operational modes for adaptive optoelectronic camouflage sheets. These devices are capable of producing black-and-white patterns that spontaneously match those of the surroundings, without user input or external measurement. Systematic experimental, computational, and analytical studies of the optical, electrical, thermal, and mechanical properties reveal the fundamental aspects of operation and also provide quantitative design guidelines that are applicable to future embodiments.

Buildings consume about 40% of global energy. It is essential to use various measures to reduce the energy consumption of the buildings as much as possible. This research investigates the impact of using a new combination of thermochromic (TC) materials in the building envelope of educational buildings. A case study building at Razi University was selected, and a 3D model was created in DesignBuilder software. Firstly, TC coating for external walls was entered into the base model, and several simulations were performed to find the effect of this coating on the energy consumption of the building. Then, a low-emissivity thermochromic (LETC) window was defined using energy management system (EMS) scripting and was entered into the base model. Finally, these two measures were combined, and the cumulative effect of using both TC coating on the external walls and LETC window was identified. Results indicated that the simultaneous application of these two measures reduced the heating demand of the building more in Tabriz, with the least cooling degree days (CDD). Also, simulation results revealed that the simultaneous use of these measures decreased the cooling demand of the building more in Bandar Abbas, with the highest CDD. Using TC coating on the external walls and LETC windows together reduced the energy consumption of the building more in Bandar Abbas. Consequently, integrating these measures can reduce the heating demand of educational buildings more in heating-dominated climates. Also, the simultaneous use of these measures can reduce cooling demand more in cooling-dominated climates.

A coating with thermochromic and photochromic microcapsules can enhance a product’s attractiveness. Different coating processes may affect the performance of coatings. Therefore, the micromorphology, chemical composition, chromatic difference, gloss, hardness, adhesion, impact resistance, roughness, cold liquid resistance, and ultraviolet photooxidation resistance of the surface coating on the metal substrate were assessed by choosing three coating processes. The thermochromic color difference of the coating with photochromic microcapsules in the primer and thermochromic microcapsules in the topcoat changes greatly. When the temperature reached 80 °C, the maximum color difference of the coating was found to be 23.0. The color difference of the coating with the thermochromic microcapsules in the primer and photochromic microcapsules in the topcoat was the most obvious, with a color difference of 71.7. The gloss of the coating mixed with thermochromic microcapsules and photochromic microcapsules was the highest, which was found to be 81.7 GU. The coating gloss of thermochromic microcapsules in the primer and photochromic microcapsules in the topcoat was found to be 15.6. The mechanical property of the coating mixed with thermochromic microcapsules and photochromic microcapsules was the best—the hardness was found to be 2H, the adhesion was found to be level 1, and the impact resistance was found to be 12.5 kg·cm. The mechanical property of the coating prepared by the other two coating sequences was poor. The coating prepared by the three finishing processes on the metal substrate had sufficient cold liquid resistance, and the gloss of the coating before and after the cold liquid resistance changed slightly. By studying the coating process of thermochromic coating and photochromic coating, a technical reference is provided for creating dual-function intelligent coatings.

Smart radiative cooling devices based on thermochromic materials such as vanadium dioxide (VO ) are of practical interest for temperature regulation and artificial homeostasis, i.e., maintaining stable equilibrium conditions for survival, both in terrestrial and space applications. In traditional solar reflector configurations, solar absorption in the VO layer is a performance limiting factor due to the multiple reflections of sunlight in the stack. Here, we demonstrate a visually transparent, smart radiator panel with reduced solar absorption. An Al-doped ZnO transparent conducting oxide layer acts as a frequency selective infrared back-reflector with high transmission of solar radiation. In this study we make use of high-quality VO thin films deposited using atomic layer deposition and optimized annealing process. Patterning of the VO layer into a metasurface results in a further reduction of the solar absorption parameter to around 0.3, while exhibiting a thermal emissivity contrast Δ of 0.26 by exploiting plasmonic enhancement effects. The VO metasurface provides a visual spectrum transmission of up to 62%, which is of interest for a range of applications requiring visual transparency. The transparent smart metasurface thermal emitter offers a new approach for thermal management in both space and terrestrial radiative cooling scenarios.