Bioinspired thermochromic transparent hydrogel wood with advanced optical regulation abilities and mechanical properties for windows

Liu, Sai; Tso, Chi Yan; Du, Yuwei; Chao, Luke; Lee, Hau Him; Ho, Tsz Chung; Leung, Mkh

doi:10.1016/j.apenergy.2021.117207

Cited by 53 publications

(23 citation statements)

References 51 publications

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“…In order to reveal the chemical composition and chemical interactions of the hydrogel, the FTIR spectra of Hydrogel-10.6 (opaque at 35 °C), Hydrogel-10.6 (transparent), NIPAM, AM, and SDS are demonstrated in Figure d. The three characteristic absorption peaks at around 1626 cm –1 (amide I band, CO stretching), 1546 cm –1 (amide II band, N–H bending), and 1459 cm –1 (CO bond) in the spectrum of Hydrogel-10.6 could be attributed to the three corresponding characteristic peaks of NIPAM and AM. , In the Hydrogel-10.6 spectrum, two characteristic peaks at around 1387 and 1368 cm –1 were discovered, which could be attributed to the deformation vibration of the C–H bond of the isopropyl group of NIPAM . Three prominent vibrations at 2917, 2850, and 1218 cm –1 in the Hydrogel-10.6 spectrum could be assigned to the antisymmetric CH 2 stretching, symmetric CH 2 stretching, and SO stretching vibration of SDS, respectively.…”

Section: Resultsmentioning

confidence: 99%

Dual-Responsive Hydrogels with Three-Stage Optical Modulation for Smart Windows

Dai

Zhao

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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Since room temperature management consumes a large amount of building energy, thermochromic smart windows have been extensively used for temperature regulation and energy management. However, the development of the smart window is still limited by its simple thermochromic performance, unreasonable thermochromic temperature, and the lack of additional stimulation conditions. In this work, a dual-responsive hydrogel was developed by introducing sodium dodecyl sulfate (SDS) and sodium chloride into the cross-linking network of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylamide (PAM) for energysaving and privacy protection. By controlling the temperature from low (<15 °C) to medium (15−28 °C) to high (>28 °C), the dual-responsive hydrogel achieved a reversible three-stage transition of opaque−transparent−translucent. The hydrogel exhibited a satisfactory solar modulation ability (T lum = 80.3%, ΔT sol,15−18°C = 72.9%, ΔT sol,18−35°C = 42.7%) and effective IR and UV shielding at high (or low) temperatures. Moreover, compared with traditional windows, smart windows made of dual-responsive hydrogels could offer better thermal insulation and heat preservation. The electrochromic properties of the dual-responsive hydrogel presented a facile strategy to meet the needs of different situations. The dual-responsive hydrogel features energy-saving, privacy protection, three-stage optical modulation, and multistimulus responsiveness, making it an ideal smart window candidate.

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Section: Resultsmentioning

confidence: 99%

Dual-Responsive Hydrogels with Three-Stage Optical Modulation for Smart Windows

Dai

Zhao

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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“…The outstanding mechanical behavior of wood hydrogels is reflected not only in mechanical strength but also in flexibility. 34 To evaluate the significant mechanical performance triggered by the distinct structure of wood-based samples (NW, DW, TW, and Bi-N-CDs/BiOBr@TW), tensile tests were developed along both R-and A-directions, as shown in Figure 4a,b. Compared to the three other wood-based samples, NW samples exhibit relatively low strength (0.7 and 3.02 MPa) in both R-and A-directions due to the existence of lignin conferring NW rigidity.…”

Section: Chemical and Compositionalmentioning

confidence: 99%

A Transparent, High-Strength, and Recyclable Core–Shell Structured Wood Hydrogel Integrated with Carbon Dots for Photodegradation of Rhodamine B

Yue

2023

ACS Appl. Nano Mater.

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The opacity, fragility, and environmental unfriendliness of the traditional photocatalytic matrix cannot fully utilize the properties of photocatalysts and efficiently degrade pollutants. In this work, a transparent wood hydrogel with a core–shell structure was developed using transparent wood (TW) impregnated with polyacrylic acid (PAA) as the core layer and Bi-N-carbon dots/BiOBr (Bi-N-CDs/BiOBr) photocatalyst-initiated polymerization of acrylic acid (AA) monomers as the shell layer. In the shell layer, nanoscale CDs with rich hydrophilic groups built a link between BiOBr and PAA and strengthened the adsorption–photocatalysis synergistic removal for RhB. The original wood backbone well conserved during preparation led to an anisotropic structure in the resultant Bi-N-CDs/BiOBr@TW photocatalytic wood hydrogel. Namely, after introducing Bi-N-CDs/BiOBr as the linker and reinforcing agent, the tensile strength was up to 3.2 and 11.03 MPa along the radial (R-) and axial (A-) directions, which was 1.6- and 1.06-fold of R-TW and A-TW, respectively. Hence, Bi-N-CDs/BiOBr@TW with high strength furnishes multiple separations and reutilizations, and the RhB removal rate is approximately 85% after five cycles. The Bi-N-CDs/BiOBr@TW exhibited light transmittance up to 64.6 and 52.3% at 800 nm along the R- and A-directions, respectively. Moreover, the adsorption–photocatalysis synergistic rate of Bi-N-CDs/BiOBr@TW reached 93% in 300 min at pH = 7. This paper offers a strategy for fabricating wood hydrogels with outstanding stretchability, transparency, dye removal efficiency, and recyclability, opening a significant route for alleviating dye pollution.

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“…Stimuli-responsive switchable hybrid perovskite materials display reversible color changes, fluorescence, phase transition, or other physical properties under external stimulations, including temperature, light, pressure, and electricity, and play an important role in energy-saving and environmental protection. − Besides, these materials also have great potential for applications in smart windows, storage devices, sensors, optoelectronic devices, switch operations, and so on. − Among them, thermochromic hybrid perovskites, possessing the interesting stimulation response of color change under varying temperatures, have emerged as good candidates due to their wide applications in smart temperature coatings, colored clothing, smart stealth materials, and temperature sensors. − Generally, thermochromism, caused by phase transition or vibronic coupling, is a notable color-change phenomenon and is often present in Cu-based and Pb-based hybrid perovskites. − More glaringly, compared with the high toxicity of Pb-based perovskites, Cu-based perovskites are excellent candidates for thermochromic materials. The 2D [CuX 4 ] 2– layers were separated by the organic cations in 2D OIHPs. , As a result of the Jahn–Teller effect, two of the six Cu–X bonds are longer than the others combining with the distorted [CuX 4 ] 2– layer, which result in additional flexibility of the inorganic framework .…”

Section: Introductionmentioning

confidence: 99%

Switchable Dielectric Two-Dimensional Lead-Free Perovskite with Reversible Thermochromic Response

Zhang

et al. 2022

J. Phys. Chem. C

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Two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs) have attracted great interest due to their unique properties for optical, thermal, electric, force, and magnetic applications. However, although some 2D HOIPs with thermochromic properties have been obtained, the issue of toxicity of lead and single-stimulus response impose restrictions on their further applications. To overcome this limitation, we scientifically design and fabricate a novel two-dimensional organic–inorganic hybrid lead-free perovskite [2,5-DCA]2·[CuCl4] (1), which simultaneously possesses excellent reversible chromic/dielectric response under thermal stimulation. Specifically, along with the change in temperature (303–413 K), crystal 1 displays a reversible color change between yellow-green and red-brown with a band gap variation from 2.25 to 2.05 eV. Besides, compared with other thermochromic perovskites, crystal 1 also exhibits a sensitive dielectric transition at a lower phase-transition point (around 369 K) with high fatigue resistance. This study demonstrates a reliable strategy for the fabrication of multiple-stimuli-responsive materials and sheds light on the study of two-dimensional lead-free perovskites in smart windows.

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Bioinspired thermochromic transparent hydrogel wood with advanced optical regulation abilities and mechanical properties for windows

Cited by 53 publications

References 51 publications

Dual-Responsive Hydrogels with Three-Stage Optical Modulation for Smart Windows

Dual-Responsive Hydrogels with Three-Stage Optical Modulation for Smart Windows

A Transparent, High-Strength, and Recyclable Core–Shell Structured Wood Hydrogel Integrated with Carbon Dots for Photodegradation of Rhodamine B

Switchable Dielectric Two-Dimensional Lead-Free Perovskite with Reversible Thermochromic Response

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