Bright and Switchable Whiteness in Macro-Crosslinked Hydrogels
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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9
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Advanced Optical Materials, Volume 12, issue 11
Abstract
Bright white color is often achieved in nature by the combination of polydisperse scattering structures and high refractive index contrast between the scatterer and the surrounding medium. Similarly, synthetic systems have commonly utilized inorganic materials as the scattering centers to achieve white color, which, however, lacks the ability to switch the optical properties. While hydrogels capable of scattering light are utilized in applications such as smart windows, their reflection properties have remained limited due to the low refractive index contrast between the polymer and water. As a result, thick layers in the millimeter range are often required to achieve reasonable whiteness. Here a hydrogel consisting of a temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) and chemically modified agarose used as a chemical macro-crosslinker is presented. The hydrogel exhibits high whiteness at temperatures above the phase transition (≈31 °C). The reflectance at 800 nm is four times as high as for standard PNIPAm, and a change in transmittance can be induced by laser pulses as short as 30 ms. The macro-crosslinked structure of this hydrogel provides superior reflectance at a lower thickness compared to reported hydrogel systems, enabling a variety of potential applications including smart windows, responsive displays, optical switches, and camouflage.Description
Funding Information: A.E. and S.H. contributed equally to this work. The authors acknowledge the provision of facilities and technical support by Aalto University at OtaNano ‐ Nanomicroscopy Center (Aalto‐NMC) and funding from Academy of Finland (Postdoctoral Researcher No. 331015 to H.Zhang, Center of Excellence in Life‐Inspired Hybrid Materials–LIBER No. 346108 to O.I. and No. 346107 to A.P., and Flagship PREIN No. 320165 to A.P.), China Scholarship Council (No. 202207960015 to Y.F.), and the European Research Council (Advanced Grant DRIVEN No. 742829 to O.I., Consolidator Grant MULTIMODAL No. 101045223 to A.P., and Starting Grant ONLINE No. 101076207 to H.Zeng). | openaire: EC/H2020/742829/EU//DRIVEN Publisher Copyright: © 2023 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH.
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Eklund, A, Hu, S, Fang, Y, Savolainen, H, Pi, H, Zeng, H, Priimagi, A, Ikkala, O & Zhang, H 2024, 'Bright and Switchable Whiteness in Macro-Crosslinked Hydrogels', Advanced Optical Materials, vol. 12, no. 11, 2302487. https://doi.org/10.1002/adom.202302487