Responsive Chiral Photonic Cellulose Nanocrystal Materials

Advanced Optical Materials, Год журнала: 2022, Номер 10(22)

Опубликована: Сен. 6, 2022

Abstract Responsive photonic crystals have attracted significant attention in fundamental scientific research and technological applications. Upon applying external stimuli, such as mechanical, electrical, magnetic, optical triggers, the properties of can be actively tuned. Among a large number crystals, cellulose nanocrystals (CNCs) are considered one most promising materials due to their renewability, simplicity preparation, unprecedented chirality. A comprehensive overview design principles, methodologies, responsive mechanisms, practical applications chiral CNC is presented here. The changes helix pitch, refractive index, orientation, resulting structural CNCs response various stimuli discussed. Thereafter, novel CNCs, colorimetric sensors, actuators, rewritable papers, anti‐counterfeiting smart tags described. We conclude by discussing future challenges opportunities for developing high‐performance materials.

Язык: Английский

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Optical Characteristics of Stretchable Chiral Liquid Crystal Elastomer under Multiaxial Stretching

Advanced Functional Materials, Год журнала: 2023, Номер 33(46)

Опубликована: Июль 6, 2023

Abstract Chiral liquid crystal elastomers (CLCEs) are soft photonic materials that exhibit both the characteristics of nanoscale periodic helical structures and mechanical properties rubber. Owing to its elasticity, structural color CLCEs can be tuned through deformations known as mechanochromism. Thus far, there is significant research attention exploring mechanochromism CLCEs. However, most studies have only discussed shifting under uniaxial deformation. Therefore, optical chiral deformation behaviors multiaxial stress not well understood. This study investigates (uniaxial, biaxial, out‐of‐plane) stretching‐induced structure change resulting The results confirm stretching leads a loss intrinsic circular polarization selectivity in due helix unwinding deformations, while biaxial out‐of‐plane maintain polarization.

Язык: Английский

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Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles

Advanced Optical Materials, Год журнала: 2023, Номер 11(19)

Опубликована: Июль 9, 2023

Abstract Cholesteric liquid crystals (CLCs) are becoming increasingly popular due to their unique chiral structural color. Unlike ordinary CLCs materials, particles exhibit angle‐independence, making them particularly noteworthy. However, currently, there limited effective methods for controlling the color of particles, other than adjusting concentration dopants or introducing stimuli‐responsive groups. Here, a scalable and cost‐effective process preparing monodisperse via dispersion polymerization is reported. By into micrometer‐sized spheres, helical pitch can be varied according its particle size, resulting hue Bragg reflection also changed. Covering with polydimethylsiloxane results in formation polymer dispersed crystals–like structure, which enhances appearance thermal stability particles. Additionally, simple strategy produce anti‐counterfeiting QR codes developed. combining commercially available pigments, an code that only displayed under specific circular polarizer created. This approach expand modulation enrich application field optical anti‐counterfeiting.

Язык: Английский

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Fundamental Aspects of Stretchable Mechanochromic Materials: Fabrication and Characterization

Materials, Год журнала: 2024, Номер 17(16), С. 3980 - 3980

Опубликована: Авг. 10, 2024

Mechanochromic materials provide optical changes in response to mechanical stress and are of interest a wide range potential applications such as strain sensing, structural health monitoring, encryption. Advanced manufacturing 3D printing enables the fabrication complex patterns geometries. In this work, classes stretchable mechanochromic that visual color when tension is applied, namely, dyes, polymer dispersed liquid crystals, crystal elastomers, cellulose nanocrystals, photonic nanostructures, hydrogels, hybrid systems (combinations other classes) reviewed. For each class, synthesis processing, well mechanism change discussed. To enable selection across classes, sensitivity different compared. Photonic demonstrate high (Δnm/% strain), large dynamic range, rapid reversibility. Further, behavior can be predicted using simple model. with properties (elastic modulus) have been achieved. The addition dyes has broadened i.e., over which there an change. irreversible desired, dye-based or elastomer formulated. While many promising demonstrated, uniform on scale remains challenge. Standardized characterization methods needed translate practical applications. sustainability also important consideration.

Язык: Английский

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Laser Written Stretchable Diffractive Optic Elements in Liquid Crystal Gels

Crystals, Год журнала: 2022, Номер 12(10), С. 1340 - 1340

Опубликована: Сен. 22, 2022

Direct laser writing (DLW) in liquid crystals (LCs) enables a range of new stimuli-responsive functionality to be realized. Here, method fabricating mechanically tunable diffraction gratings stretchable LC gels is demonstrated using combination two-photon polymerization direct (TPP-DLW) and ultraviolet (UV) irradiation. Results are presented that demonstrate the fabrication grating written TPP-DLW presence an electric field order align lock-in director homeotropic configuration. The subsequently removed surrounding regions layer then exposed UV light freeze-in different alignment so as ensure there phase difference between illuminated polymerized regions. It found change period when observed on polarizing optical microscope well far-field pattern film stretched or contracted. These experimental results compared with from simulations. paper concludes demonstration tuning 2-dimensional grating.

Язык: Английский

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Effect of Crosslinkers on Optical and Mechanical Behavior of Chiral Nematic Liquid Crystal Elastomers

Molecules, Год журнала: 2021, Номер 26(20), С. 6193 - 6193

Опубликована: Окт. 14, 2021

Chiral nematic (N*) liquid crystal elastomers (LCEs) are suitable for fabricating stimuli-responsive materials. As crosslinkers considerably affect the N*LCE network, we investigated effects of crosslinking units on physical properties N*LCEs. The N*LCEs were synthesized with different types crosslinkers, and relationship between N*LC polymeric system unit was investigated. emit color by selective reflection, in which changes response to mechanical deformation. LC-type crosslinker decreases helical twisting power increasing total molar ratio mesogenic compound. exhibits mechano-responsive coupling orientation polymer where exhibit degrees pitch variation depending crosslinker. Moreover, increases Young's modulus N*LCEs, long methylene chains increase breaking strain. An analysis experimental results verified effect providing a design rationale materials mechano-optical sensor applications.

Язык: Английский

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Orientation of Liquid Crystalline Molecules on PDMS Surfaces and within PDMS Microfluidic Systems

Applied Sciences, Год журнала: 2021, Номер 11(24), С. 11593 - 11593

Опубликована: Дек. 7, 2021

The unique components of PDMS-based microfluidic systems are those combined with liquid crystalline materials. Their functionality, especially when it comes to optical applications, highly depends on the LC molecular arrangement. This work summarizes experimental investigations orientation molecules within LC:PDMS structures according manufacturing technologies. availability high-quality molds pattern PDMS is a significant barrier creation advanced systems. possibility using inexpensive in rapid and reproducible fabrication process has been particularly examined as an alternative photolithography. Different geometries, including innovative approach for electrical control arrangement microchannels, presented. These studies critical novel optofluidic systems, introducing further research waveguiding structures.

Язык: Английский

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Tunable Reflection through Size Polydispersity of Chiral-Nematic Liquid Crystal Polymer Particles

Molecules, Год журнала: 2023, Номер 28(23), С. 7779 - 7779

Опубликована: Ноя. 25, 2023

Micro-sized chiral-nematic liquid crystal (N* LC) polymer particles have attracted considerable interest as versatile reflective colorants with selective circularly polarized light (CPL) properties. However, challenges in achieving the desired size distribution of N* LC led to an incomplete understanding their characteristics. In this study, we successfully synthesized via dispersion polymerization, enabling precise control over polydispersity by manipulating composition polymerization solvent. Our investigation revealed that monodisperse displayed distinct reflection bands high CPL selectivity, while polydisperse exhibited broader lower selectivity. These findings underscore potential synthesize tailored properties using identical monomeric compounds. Furthermore, demonstrated production multifunctional blending varying colors. discoveries hold significant promise for advancing development and anti-counterfeiting printing techniques utilizing micro-sized particles.

Язык: Английский

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Angular-Dependent Back-Reflection of Chiral-Nematic Liquid Crystal Microparticles as Multifunctional Optical Elements

Crystals, Год журнала: 2023, Номер 13(12), С. 1660 - 1660

Опубликована: Дек. 3, 2023

The development of multifunctional optical elements capable controlling polarization, wavelength, and propagation direction is pivotal for the miniaturization devices. However, designing spatial distribution refractive index fabrication such remains challenging. This study demonstrates spectroscopic function microparticles composed chiral-nematic liquid crystals (N* LC), which inherently selectively reflect circularly polarized light. measurement reflection spectra with fiber probes revealed angular-dependent back-reflection single layer N* LC particles. These results indicate that our possess multiple functions, enabling separation incident light polarization wavelength within a material. suggests broad applications particles as compact elements.

Язык: Английский

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In‐Plane Uniaxial Helical‐Axis Alignment in Chiral‐Nematic Liquid Crystal Polymer Films Using Photogradient Polymerization

Small Structures, Год журнала: 2024, Номер unknown

Опубликована: Ноя. 3, 2024

Chiral‐nematic liquid‐crystal (N* LC) polymer films with uniaxially controlled helical‐axis alignments have attracted increasing attention for developing next‐generation materials promising mechanical, optical, and electronic properties. These functionalities in N* LC can be realized by controlling their alignment. However, achieving precise control over alignment remains challenging. This study presents a simple effective method uniaxial through photogradient polymerization. approach induces direction‐controlled isotropic‐to‐N* phase transition driven concentration gradient, resulting along the direction. The proposed offers valuable insights facile fabrication of alignments.

Язык: Английский

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