Cholesteric liquid crystal films with adjustable wavelength band and reflectance by using wash-out/refill technique and light-responsive compounds

Shi, Weiting; Han, Rui; Zhang, Xuetao; Li, Hui; Cao, Hui; Chen, Yinjie; Wang, Dong; Yang, Zhou; He, Wanli

doi:10.1080/02678292.2022.2065374

Cited by 3 publications

(3 citation statements)

References 26 publications

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“…A photochromic, light-reflecting, and temperature-responsive polymer thin film was presented by Shi et al [217]. The material comprised polymerizable liquid crystals that create a net for inserting free liquid crystals and additives.…”

Section: Systems Responsive To Lightmentioning

confidence: 99%

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity

et al. 2023

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Two-dimensional and pseudo-2D systems come in various forms. Membranes separating protocells from the environment were necessary for life to occur. Later, compartmentalization allowed for the development of more complex cellular structures. Nowadays, 2D materials (e.g., graphene, molybdenum disulfide) are revolutionizing the smart materials industry. Surface engineering allows for novel functionalities, as only a limited number of bulk materials have the desired surface properties. This is realized via physical treatment (e.g., plasma treatment, rubbing), chemical modifications, thin film deposition (using both chemical and physical methods), doping and formulation of composites, or coating. However, artificial systems are usually static. Nature creates dynamic and responsive structures, which facilitates the formation of complex systems. The challenge of nanotechnology, physical chemistry, and materials science is to develop artificial adaptive systems. Dynamic 2D and pseudo-2D designs are needed for future developments of life-like materials and networked chemical systems in which the sequences of the stimuli would control the consecutive stages of the given process. This is crucial to achieving versatility, improved performance, energy efficiency, and sustainability. Here, we review the advancements in studies on adaptive, responsive, dynamic, and out-of-equilibrium 2D and pseudo-2D systems composed of molecules, polymers, and nano/microparticles.

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Section: Systems Responsive To Lightmentioning

confidence: 99%

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity

et al. 2023

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“…Radka et al adopted this double-layer-stacked configuration using two oppositely handed polymer-stabilized CLCs and demonstrated electro-mechanically induced tuning in reflectivity of a hyper-reflection bandgap at a certain wavelength and splitting as well as broadening in bandgaps [ 34 ]. Another widely investigated approach is to acquire hyper-reflectivity in a single polymer-stabilized CLC cell by injecting an LH (RH)-CLC into a cell containing an RH (LH) polymer network template based on the wash-out/refill method [ 35 , 36 , 37 ]. For practical applications, however, the fabrication procedure is relatively complicated, and the resultant bandgap properties can hardly be modulated by an externally applied electric field.…”

Section: Introductionmentioning

confidence: 99%

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses

Tseng,

Wu,

Lee

2024

Molecules

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We propose a double-cell cholesteric liquid crystal (CLC) device composed of a left-handed (LH) CLC cell with a pair of sheet electrodes and a right-handed (RH) CLC cell with a tri-electrode configuration characterized by a sheet electrode on the top and an interdigitated electrode on the bottom substrates. Bi-reflected color tuning and hyper-reflective color switching are revealed from this cell stack via the electrothermal control of the central wavelengths of the LH- and RH-bandgaps by voltage-induced pseudo-dielectric heating. The two CLCs are thermally sensitive and exhibit overlapped bandgaps in the field-off state with nearly identical temperature dependence, resulting in a hyper-reflective color at 720 nm at 23.4 °C and 380 nm at 29.8 °C. Upon the application of 4 Vrms at 2 MHz across the stacked device to induce pseudo-dielectric heating, two reflective colors can be resolved due to asymmetrical temperature elevations. Accordingly, the difference in wavelength between the two colors increases with increasing voltage through a series cell connection, while maintaining approximately constant via a parallel connection. This study provides a feasible pathway to developing a multifunctional device with electrothermally tunable bi-reflected and hyper-reflective states based on two conventional cell geometries, which is promising for lasers and color-related display applications.

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“…To address these issues, easy operation, preparation, anti-contamination, and stable treatment methods that combine polymers and small-molecule LCs have been proposed. [52][53][54][55][56][57][58] Usually, the crosslinked network in polymer film can not only fix the mesogenic orientation but also serve as a diffusion channel for substances. Although the addition of a polymer matrix successfully decreases the fluidity, it introduces intermolecular forces to LC systems, reducing their stimuli-responsive properties, and thus this approach is usually confined to a hard glass substrate.…”

Section: Introductionmentioning

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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Cholesteric liquid crystal films with adjustable wavelength band and reflectance by using wash-out/refill technique and light-responsive compounds

Cited by 3 publications

References 26 publications

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

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