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Fast Switching of Bright Whiteness in Channeled Hydrogel Networks

Tutkimustuotosvertaisarvioitu

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Fast Switching of Bright Whiteness in Channeled Hydrogel Networks. / Eklund, Amanda; Zhang, Hang; Zeng, Hao; Priimägi, Arri; Ikkala, Olli.

julkaisussa: Advanced Functional Materials, 2020.

Tutkimustuotosvertaisarvioitu

Harvard

APA

Eklund, A., Zhang, H., Zeng, H., Priimägi, A., & Ikkala, O. (2020). Fast Switching of Bright Whiteness in Channeled Hydrogel Networks. Advanced Functional Materials, [2000754]. https://doi.org/10.1002/adfm.202000754

Vancouver

Author

Eklund, Amanda ; Zhang, Hang ; Zeng, Hao ; Priimägi, Arri ; Ikkala, Olli. / Fast Switching of Bright Whiteness in Channeled Hydrogel Networks. Julkaisussa: Advanced Functional Materials. 2020.

Bibtex - Lataa

@article{b31e95cd53674c009a195edc3895246f,
title = "Fast Switching of Bright Whiteness in Channeled Hydrogel Networks",
abstract = "Beside pigment absorption and reflection by periodic photonic structures, natural species often use light scattering to achieve whiteness. Synthetic hydrogels offer opportunities in stimuli-responsive materials and devices; however, they are not conventionally considered as ideal materials to achieve high whiteness by scattering due to the ill-defined porosities and the low refractive index contrast between the polymer and water. Herein, a poly(N-isopropylacrylamide) hydrogel network with percolated empty channels (ch-PNIPAm) is demonstrated to possess switchable bright whiteness upon temperature changes, obtained by removing the physical agarose gel in a semi-interpenetrating network of agarose and PNIPAm. The hydrogel is highly transparent at room temperature and becomes brightly white above 35 °C. Compared to conventional PNIPAm, the ch-PNIPAm hydrogel exhibits 80{\%} higher reflectance at 800 nm and 18 times faster phase transition kinetics. The nanoscopic channels in the ch-PNIPAm facilitate water diffusion upon phase transition, thus enabling the formation of smaller pores and enhanced whiteness in the gel. Furthermore, fast photothermally triggered response down to tens of milliseconds can be achieved. This unique property of the ch-PNIPAm hydrogel to efficiently scatter visible light can be potentially used for, e.g., smart windows, optical switches, and, as demonstrated in this report, thermoresponsive color displays.",
keywords = "double networks, hydrogels, interpenetrating networks, lower critical solution temperature, whiteness",
author = "Amanda Eklund and Hang Zhang and Hao Zeng and Arri Priim{\"a}gi and Olli Ikkala",
year = "2020",
doi = "10.1002/adfm.202000754",
language = "English",
journal = "Advanced Functional Materials",
issn = "1616-301X",
publisher = "WILEY-V C H VERLAG GMBH",

}

RIS (suitable for import to EndNote) - Lataa

TY - JOUR

T1 - Fast Switching of Bright Whiteness in Channeled Hydrogel Networks

AU - Eklund, Amanda

AU - Zhang, Hang

AU - Zeng, Hao

AU - Priimägi, Arri

AU - Ikkala, Olli

PY - 2020

Y1 - 2020

N2 - Beside pigment absorption and reflection by periodic photonic structures, natural species often use light scattering to achieve whiteness. Synthetic hydrogels offer opportunities in stimuli-responsive materials and devices; however, they are not conventionally considered as ideal materials to achieve high whiteness by scattering due to the ill-defined porosities and the low refractive index contrast between the polymer and water. Herein, a poly(N-isopropylacrylamide) hydrogel network with percolated empty channels (ch-PNIPAm) is demonstrated to possess switchable bright whiteness upon temperature changes, obtained by removing the physical agarose gel in a semi-interpenetrating network of agarose and PNIPAm. The hydrogel is highly transparent at room temperature and becomes brightly white above 35 °C. Compared to conventional PNIPAm, the ch-PNIPAm hydrogel exhibits 80% higher reflectance at 800 nm and 18 times faster phase transition kinetics. The nanoscopic channels in the ch-PNIPAm facilitate water diffusion upon phase transition, thus enabling the formation of smaller pores and enhanced whiteness in the gel. Furthermore, fast photothermally triggered response down to tens of milliseconds can be achieved. This unique property of the ch-PNIPAm hydrogel to efficiently scatter visible light can be potentially used for, e.g., smart windows, optical switches, and, as demonstrated in this report, thermoresponsive color displays.

AB - Beside pigment absorption and reflection by periodic photonic structures, natural species often use light scattering to achieve whiteness. Synthetic hydrogels offer opportunities in stimuli-responsive materials and devices; however, they are not conventionally considered as ideal materials to achieve high whiteness by scattering due to the ill-defined porosities and the low refractive index contrast between the polymer and water. Herein, a poly(N-isopropylacrylamide) hydrogel network with percolated empty channels (ch-PNIPAm) is demonstrated to possess switchable bright whiteness upon temperature changes, obtained by removing the physical agarose gel in a semi-interpenetrating network of agarose and PNIPAm. The hydrogel is highly transparent at room temperature and becomes brightly white above 35 °C. Compared to conventional PNIPAm, the ch-PNIPAm hydrogel exhibits 80% higher reflectance at 800 nm and 18 times faster phase transition kinetics. The nanoscopic channels in the ch-PNIPAm facilitate water diffusion upon phase transition, thus enabling the formation of smaller pores and enhanced whiteness in the gel. Furthermore, fast photothermally triggered response down to tens of milliseconds can be achieved. This unique property of the ch-PNIPAm hydrogel to efficiently scatter visible light can be potentially used for, e.g., smart windows, optical switches, and, as demonstrated in this report, thermoresponsive color displays.

KW - double networks

KW - hydrogels

KW - interpenetrating networks

KW - lower critical solution temperature

KW - whiteness

U2 - 10.1002/adfm.202000754

DO - 10.1002/adfm.202000754

M3 - Article

JO - Advanced Functional Materials

JF - Advanced Functional Materials

SN - 1616-301X

M1 - 2000754

ER -