Optical Properties of Thermotropic Hydrogels (a Review)

Maiorov, V. A.

doi:10.1134/s0030400x20030133

Cited by 7 publications

(5 citation statements)

References 58 publications

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“…Thermotropic hydrogels are commonly produced from synthetic polymers or biopolymers (Resch & Wallner, 2009). As a typical member of synthetic polymers, poly(N-isopropylacrylamide) (PNIPAm) has been extensively investigated due to its unique features, such as reversible abrupt transparent-opaque transition, good resistance to UV radiation and simplicity of synthesis (Maiorov, 2020;Wang et al, 2014). Pure PNI-PAm hydrogels have an LCST of approximately 32 °C (Nun et al, 2017).…”

Section: Dynamic Optical Characteristics Of Thermotropic Hydrogelsmentioning

confidence: 99%

“…Its advantages over synthetic polymers regarding price and availability make it economically feasible for large scale applications (Resch & Wallner, 2009). Furthermore, the scattering domain sizes of HPC hydrogels could reach as high as 1-2 μm in diameter; therefore, radiation in both the visible and NIR regions can be effectively scattered (Maiorov, 2020;Yang et al, 2016). As illustrated in Fig.…”

Section: Dynamic Optical Characteristics Of Thermotropic Hydrogelsmentioning

confidence: 99%

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A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control

Liu

Wu²

2022

ARIN

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Efficient management of solar radiation through architectural glazing is a key strategy for achieving a comfortable indoor environment with minimum energy consumption. Conventional glazing consisting of a single or multiple glass pane(s) exhibits high visible light transmittance and solar heat gain coefficient, which can be a double-edged sword, i.e., it allows sufficient sunlight to enter the building interior space for passive heating and lighting; on the other hand, it can cause glare discomfort and large cooling energy consumption. Among the various advanced glazing technologies being developed, Building Integrated Photovoltaic (BIPV) glazing has a prominent position due to its ability to reduce cooling load and visual discomfort while simultaneously generating electricity from sunlight. Recent years have witnessed remarkable advances in low-concentration optics such as Dielectric based Compound Parabolic Concentrators (DiCPCs), with a growing interest in the development of Building Integrated Concentrating Photovoltaic (BICPV) glazing to improve light harvesting and electric power output. One of the challenges faced by traditional BIPV glazing systems is the lack of dynamic control over daylight and solar heat transmission to cope with variations in weather conditions and seasonal heating/cooling demands of buildings. A promising solution is to integrate an optically switchable smart material into a BIPV glazing system, which enables dynamic daylighting control in addition to solar power conversion. Thermotropic (TT) hydrogel materials such as poly(N-isopropylacrylamide) (PNIPAm) and Hydroxypropyl Cellulose (HPC) are potential candidates for hybrid BIPV smart glazing applications, due to their unique features such as high visible transparency (in the clear state), strong light-scattering capability (in the translucent state) and large solar energy modulation. This paper reviews various types of electricity-generating glazing technologies including BIPV glazing and BICPV glazing, as well as smart glazing technologies with a particular focus on TT hydrogel integrated glazing. The characteristics, benefits and limitations of hybrid BIPV smart glazing are also evaluated. Finally, the challenges and research opportunities in this emerging field are discussed.

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Section: Dynamic Optical Characteristics Of Thermotropic Hydrogelsmentioning

confidence: 99%

Section: Dynamic Optical Characteristics Of Thermotropic Hydrogelsmentioning

confidence: 99%

A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control

Liu

Wu²

2022

ARIN

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“…39 Although the number of efforts on integrating hydrogels with optical fibers has been surging in recent years, this field has never been reviewed extensively and hence a comprehensive look into the literature can benefit both new researchers and those who have been guiding the field. We note that while several reviews discuss hydrogel optics 40 and hydrogel-based sensors, 41–44 those discussions are rather brief and not comprehensive enough for hydrogel-integrated optical fibers, optical fiber sensing principles, and their applications.…”

Section: Introductionmentioning

confidence: 99%

Hydrogel-integrated optical fiber sensors and their applications: a comprehensive review

et al. 2023

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“…[8,16] Using stimuli-responsive hydrogels that undergo phase separation under certain conditions has led to advances in improving the scattering properties in hydrogel systems and polymer solutions. [18] Both hydroxypropyl cellulose [19][20][21][22][23] (HPC) and poly(N-isopropylacrylamide) [3,[23][24][25] (PNIPAm) are often used in such contexts as they become opaque upon heating due to phase transitions in solubility. [5,26] Commonly these systems are optimized for use in smart windows to regulate the indoor temperature and reduce the amount of energy used for cooling by blocking sunlight as temperature is increased above the transition temperature.…”

Section: Introductionmentioning

confidence: 99%

Bright and Switchable Whiteness in Macro‐Crosslinked Hydrogels

Eklund,

Hu,

Fang

et al. 2023

Advanced Optical Materials

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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.

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Optical Properties of Thermotropic Hydrogels (a Review)

Cited by 7 publications

References 58 publications

A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control

A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control

Hydrogel-integrated optical fiber sensors and their applications: a comprehensive review

Bright and Switchable Whiteness in Macro‐Crosslinked Hydrogels

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