Ultraviolet light screen using cholesteric liquid crystal capsules on the basis of selective reflection

Oh, Heemuk; Kikuchi, Hirotugu; Lee, Ji Hyun; Kim, Su Ji; Lee, Jun Bae; Cho, Moon Sun; Lee, Min Young; Okumura, Yasushi; Hong, Joo Hee; Hong, Sung Kyu

doi:10.1039/d1ra03499e

Cited by 5 publications

(2 citation statements)

References 30 publications

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“…Upon irradiation of actinic light, the arrangement of LC molecules can be changed, which causes changes in the transmittance or reflectance of CLCMCs, allowing their optical applications according to actinic light intensity. Hong's research group [118] prepared polycaprolactone (PCL)-based CLCMCs by solvent evaporation, which can selectively reflect 350-380 nm UV light in the human skin temperature range of 32 °C-36 °C by adjusting the ratio of the CLC mixture in the core of CLCMCs. Furthermore, it also has a UV blocking effect, similar to sunscreen, reducing about 6 % of direct sunlight UV from 290 nm-400 nm.…”

Section: Smart Sensormentioning

confidence: 99%

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Zhang,

Yang,

Chen

et al. 2023

Chemistry A European J

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Liquid crystals (LCs) are well known for inherent responsiveness to external stimuli, such as light, thermal, magnetic, and electric fields. Cholesteric LCs are among the most fascinating, since they possess distinctive optical properties due to the helical molecular orientation. However, the good flow, easy contamination, and poor stability of small‐molecule LCs limit their further applications, and microencapsulation as one of the most effective tools can evade these disadvantages. Microencapsulation can offer shell‐core structure with LCs in the core can strengthen their stability, avoiding interference with the environment while maintaining the stimuli‐responsiveness and optical properties. Here, we report recent progress in the fabrication and applications of cholesteric LC microcapsules (CLCMCs). We summarize general properties and basic principles, fabrication methods including interfacial polymerization, in‐situ polymerization, complex coacervation, solvent evaporation, microfluidic and polymerization of reactive mesogens, and then give a comprehensive overview of their applications in various popular domains, including smart fabrics, smart sensor, smart displays, anti‐counterfeiting, information encryption, biomedicine and actuators. Finally, we discuss the currently facing challenges and the potential development directions in this field.

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Section: Smart Sensormentioning

confidence: 99%

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Zhang,

Yang,

Chen

et al. 2023

Chemistry A European J

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“…18 The connection between LC and sunscreen is that LC is generally used as a surfactant in sunscreen. 19,20 Heemuk Oh et al 21 prepared cholesteric liquid crystal (CLC) microcapsules as sunscreen, which could reduce the UV in the range of 290-400 nm by 6%, but they used only one-handed CLC microcapsules, which caused the microcapsules to lack a blocking effect on the other kind of handed UV. 22 In this study, we studied the UV-blocking properties of nematic liquid crystals (NLCs) and chiral nematic liquid crystals (CNLCs).…”

Section: Introductionmentioning

confidence: 99%

Excellent ultraviolet‐blocking properties of chiral nematic liquid crystals

Wang

Zhang

et al. 2023

Photochem & Photobiology

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We report the evaluation of chiral nematic liquid crystal (CNLC) in blocking ultraviolet (UV). The CNLC was coated on a calcium fluoride substrate to measure the spectral transmittance, which was measured to detect the UV‐blocking effect of CNLC. The results show that CNLC could reduce UVB (290–320 nm) by 99.9% and UVA (320–400 nm) by 95.6%. The barrier effect of cake‐shaped semi‐solidified CNLC microspheres was further investigated, and it was found that cake‐shaped semi‐solidified CNLC microspheres could reduce UVB by 58.2% and UVA by 34.1%. This is due to the chemical absorption property of CNLC, which has UV‐absorbing functional groups such as the benzene rings. And the physical reflection properties of CNLC could periodically reflect a certain wavelength of light. Liquid crystal (LC) is a rich set of soft materials with rod‐like structures widely existing in nature, which is harmless to the human body and environment. Therefore, using CNLC's function of blocking UV, a new sunscreen can be developed.

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Short chiral pitch and blue phase stability in cholesteric liquid crystal mixtures by adding achiral benzoic acid derivative

Oh,

Yang,

Lee

et al. 2023

Liquid Crystals

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Ultraviolet light screen using cholesteric liquid crystal capsules on the basis of selective reflection

Abstract: When the prepared cholesteric liquid crystal microcapsule is applied to the skin, it can protect the skin by selectively reflecting only ultraviolet rays in sunlight like sunscreen cosmetics.

Cited by 5 publications

References 30 publications

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Excellent ultraviolet‐blocking properties of chiral nematic liquid crystals

Short chiral pitch and blue phase stability in cholesteric liquid crystal mixtures by adding achiral benzoic acid derivative

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