Multistate and On‐Demand Smart Windows

Kim, Hye-Na; Ge, Dengteng; Lee, Elaine; Yang, Shu

doi:10.1002/adma.201803847

Cited by 119 publications

(114 citation statements)

References 38 publications

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“…Controllable wrinkles possess various promising applications for flexible electronics, [ 36 ] tuned optics, [ 37 ] surface wetting, [ 4 ] cell growth template, [ 38 ] pressure sensing, [ 39 ] water harvesting, [ 40 ] and so on. Here we investigate the friction behavior of the controlled heterogeneous wrinkles.…”

Section: Resultsmentioning

confidence: 99%

Harnessing Heterogeneous Wrinkles in Metal/Polydimethylsiloxane Film System by Combination of Mechanical Loading and Heat Treatment

Shan-xin

et al. 2020

Adv Materials Inter

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dehydration, and atrophy. Controlling wrinkle morphologies including orientation, wavelength, and amplitude is very important and necessary for various practical applications.Generally, the orientation of wrinkles is determined by the stress distribution of the film. Unidirectional strain results in stripe-like wrinkles perpendicular to the strain axis [4,5] while multidirectional strain leads to disordered labyrinth-like or ordered herringbone wrinkles. [6,7] Introduction of film impurity can induce local strain anisotropy and guide wrinkle orientation, achieving highly ordered wrinkle arrays. [8,9] The wavelength of wrinkles depends on the film thickness [10] and the modulus ratio of film to substrate. [11] It can range from submicron to macroscale (kilometers in tectonic plates for instance). The amplitude of wrinkles is directly proportional to the wavelength and the square root of strain. [12,13] The aspect ratio of wrinkle (the ratio of amplitude to wavelength) is merely dependent on the strain. The previous studies showed that the wrinkle amplitude or aspect ratio is usually uniform for a homogeneous sample. [4][5][6][7] As the compression is beyond a critical value (20-30%), the homogeneous wrinkles evolve into localized patterns such as folds, ridges, and delaminations. [13][14][15][16][17] Localized wrinkles can be also observed in disordered or heterogeneous films such as single-wall carbon nanotubes, glassy polymers, and diblock copolymers due to spontaneous strain localization. [18,19] Artificial thickness or modulus inhomogeneities of film-substrate systems are frequently used to induce various complex arrays of localized patterns by mechanical loading. [20][21][22] Although localized patterns in disordered or artificially inhomogeneous systems have been extensively investigated, the formation and evolution of heterogeneous wrinkles (with unequal wavelengths or amplitudes compared with the sinusoidal wrinkles) in a homogeneous system remain unknown up to now. In this study, we report a novel way to tailor the heterogeneous wrinkles in metal/polydimethylsiloxane (PDMS) bilayer system by the combination of mechanical loading and heat treatment. The novelty of this work is concluded as following. First, the heterogeneous wrinkles in this study spontaneously form at small strain condition and evolve into homogeneous structures as the compression increases. This process is in contrast to Spontaneous wrinkled surfaces in nature usually possess unique physical and chemical properties. Inspired by nature and stimulated by practical application, artificial wrinkle patterns have received increasing interest recently. Here, the controllable heterogeneous wrinkles in metal films deposited on polydimethylsiloxane substrates by combination of mechanical loading and heat treatment is reported. It is found that the wrinkles are spontaneously localized at small strain condition due to the uneven distribution of wrinkle amplitudes on the film surface. The morphological features and underlying mechanisms of such wrink...

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Section: Resultsmentioning

confidence: 99%

Harnessing Heterogeneous Wrinkles in Metal/Polydimethylsiloxane Film System by Combination of Mechanical Loading and Heat Treatment

Shan-xin

et al. 2020

Adv Materials Inter

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“…[3,4] To decrease the impact of indoor heating and cooling on the environment, environmentally friendly and energy-saving alternatives are urgently needed. To date, several alternative technologies combining adaptive heating and cooling in one system have been developed, including smart windows, [5][6][7][8][9][10][11][12][13][14] Janus membranes, [15,16] and solar chimneys commercially available poly(dimethylsiloxane) (PDMS) precursor followed by curing in air ( Figure S1, Supporting Information). Similar to normal PDMS precursors, the emulsion needs about 6 days at room temperature to get fully cured, but could solidify within the first 20 min, accompanied by the fixation of the embedded water droplets.…”

Section: Doi: 101002/adma202000870mentioning

confidence: 99%

Switchable Cavitation in Silicone Coatings for Energy‐Saving Cooling and Heating

et al. 2020

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Space cooling and heating currently result in huge amounts of energy consumption and various environmental problems. Herein, a switching strategy is described for efficient energy‐saving cooling and heating based on the dynamic cavitation of silicone coatings that can be reversibly and continuously tuned from a highly porous state to a transparent solid. In the porous state, the coatings can achieve efficient solar reflection (93%) and long‐wave infrared emission (94%) to induce a subambient temperature drop of about 5 °C in hot weather (≈35 °C). In the transparent solid state, the coatings allow active sunlight permeation (95%) to induce solar heating to raise the ambient temperature from 10 to 28 °C in cold weather. The coatings are made from commercially available, cheap materials via a facile, environmentally friendly method, and are durable, reversible, and patternable. They can be applied immediately to various existed objects including rigid substrates.

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“…Yang's group has made great efforts in this field. [ 37,38 ] The mechanically induced transparency shift is due to the nanovoids around the nanospheres, which can be generated after deformation. Such deformation‐induced nanovoids can cause new reflective behavior of the incident light.…”

Section: Fabrication and Mechanism Of Mechanochromic Structural‐colormentioning

confidence: 99%

“…Another strategy to manipulate the scattering is to form nanovoids, which has been extensively investigated by Yang's group. [ 37,38 ] For instance, smart windows were produced with adjustable structural color and transparency based on an infiltrated photonic glass structure. [ 37 ] The photonic glass was obtained via spray‐coating a silica nanosphere dispersion on a substrate, followed by PDMS precursor infiltration to produce a photonic elastomer.…”

Section: Applications Of Mechanochromic Structural‐colored Materialsmentioning

confidence: 99%

Mechanochromism of Structural‐Colored Materials

Chen

Hong

2020

Advanced Optical Materials

134

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In comparison with pigmentary colors, structural colors are with superior chemical stability and are resistant to photobleaching, making them promising candidates for color displays. What is more, the use of toxic dyes can be avoided by utilizing structural-colored materials to display various hues. Structural colors are widespread in nature and observed in opals, [3] beetles, [4] tropical fish, [5] peacock feathers, [6] chameleons, and similar iridescent materials. [7-9] Along with the growing understanding of the morphology and mechanism of natural structural-colored materials, their artificial counterparts have been manufactured with improved performance and functions consequently. Emerging structural-colored materials can be divided into three main categories according to their nanoscale architectures: photonic crystals (PCs), [10] liquid crystals (LCs), [11] and photonic glass. [12] Due to their ability to modulate visible light, the structural-colored materials have been applied in diverse domains such as optical waveguides, [13-16] luminescence enhancement, [17-19] photo electric devices, [20,21] photocatalysts, [22,23] anti-counterfeiting technologies, [24-26] and chemical and biological sensing. [27-29] With ingenious designs of nanostructures, a variety of responsiveness has been obtained on the structural-colored materials, corresponding to varying stimuli such as temperature, [30-32] solvent, [27] gases, [28] magnetic fields, [33] and external forces. [10-12] Among them, the mechanical responsive structural colors are able to visualize invisible stress in the materials, providing effective indicators for mechanical stimuli such as stretching, compression, or bending. Such mechanochromism can be directly achieved by the deformation-induced changes in periodic lattice constants of the structural-colored materials. [34,35] Recently developed mechanochromic structuralcolored materials have extended the responsive functions from conventional mechanical stimuli to complex signals such as electric stimuli. [10] In addition, although the color shift is a predominant method to achieve mechanochromic behavior, [34-36] increasing efforts have been made to develop mechanochromism based on polarization and transparence. [11,37,38] As one of the rapidly developing intelligent materials with multiresponse, [34,39,40] mechanochromic structural-colored materials have become promising in various applications, such as mechanical sensing, [11,41] colorful displays, [10,42] anti-counterfeiting, [26,37] and healthcare materials. [43,44] In this review, we summarize recent advances in mechanochromic structural-colored materials as shown in Figure 1.

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Multistate and On‐Demand Smart Windows

Cited by 119 publications

References 38 publications

Harnessing Heterogeneous Wrinkles in Metal/Polydimethylsiloxane Film System by Combination of Mechanical Loading and Heat Treatment

Harnessing Heterogeneous Wrinkles in Metal/Polydimethylsiloxane Film System by Combination of Mechanical Loading and Heat Treatment

Switchable Cavitation in Silicone Coatings for Energy‐Saving Cooling and Heating

Mechanochromism of Structural‐Colored Materials

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