Electric Field‐Driven Control of Cholesteric Cellulose Nanocrystal Orientation and Morphology

Qu, Dan; Zussman, Eyal

doi:10.1002/adom.202101659

Cited by 14 publications

(9 citation statements)

References 46 publications

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“…For biphasic aqueous CNC suspensions exposed to external electric fields, different alignment directions were observed for freely floating tactoids, depending on the frequency of the applied AC field. , At higher frequencies (25 kHz), an alignment analogous to apolar suspensions was observed, with helical alignment perpendicular to the field, prolate tactoid distortion along the field direction and an increase in pitch. At lower frequencies (100 Hz), the opposite behavior was observed, with the helical axis reorienting to lie parallel to the field, an oblate contraction of the tactoids along the helical axis and a decrease in pitch.…”

Section: Collective Alignment Of Cncs In Suspensionmentioning

confidence: 97%

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Frka-Petesic,

Parton,

Honorato-Rios

et al. 2023

Chem. Rev.

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Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.

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Section: Collective Alignment Of Cncs In Suspensionmentioning

confidence: 97%

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Frka-Petesic,

Parton,

Honorato-Rios

et al. 2023

Chem. Rev.

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“…However, the CNC tactoids responded differently in a water solvent. [147] At low f, the tactoids exhibited anomalous negative birefringence with the helix axis lying parallel to the electric field, followed by a helix pitch decrease upon increasing E (Figure 8d). In contrast, they initially showed a positive birefringence at high f, with the helix axis perpendicular to the electric field and increasing helix pitch with E enhancement.…”

Section: Electro-responsive Chiral Photonic Cncsmentioning

confidence: 98%

“…Concentrated CNC in toluene and water solvents were reported to untwist from chiral nematic to nematic structure under an alternating current electric field. [99,100,147] Another responsive CP light reflection is realized by introducing responsive components. Using 5CB as a λ/2 retardation plate between two left-handed chiral nematic films, Fernandes et al obtained thermo-and electro-responsive reflected CP light.…”

Section: Chirality-responsive Chiral Photonic Cncsmentioning

confidence: 99%

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Responsive Chiral Photonic Cellulose Nanocrystal Materials

Rojas

Wei

et al. 2022

Advanced Optical Materials

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

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“…Like magnetic fields, alternating (AC) and direct (DC) electric fields were used to regulate CNC assembly for solid chiral nematic structures. − Diluted CNC aligns parallel to an applied AC electric field in apolar solvents due to the permanent and induced dipole moments . For concentrated CNCs, the periodicity of the liquid chiral nematic structures can be precisely manipulated on the time scale of a few seconds with the helical axis perpendicular to the electric filed at low strength .…”

Section: Evaporation-induced Self-assembly For Solid Cnc Chiral Filmsmentioning

confidence: 99%

Accelerating Cellulose Nanocrystal Assembly into Chiral Nanostructures

et al. 2023

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Cellulose nanocrystal (CNC) suspensions self-assembled into chiral nematic liquid crystals. This property has enabled the development of versatile optical materials with fascinating properties. Nevertheless, the scale-up production and commercial success of chiral nematic CNC superstructures face significant challenges. Fabrication of chiral nematic CNC nanostructures suffers from a ubiquitous pernicious trade-off between uniform chiral nematic structure and rapid self-assembly. Specifically, the chiral nematic assembly of CNCs is a time-consuming, spontaneous process that involves the organization of particles into ordered nanostructures as the solvent evaporates. This review is driven by the interest in accelerating chiral nematic CNC assembly and promoting a long-range oriented chiral nematic CNC superstructure. To start this review, the chirality origins of CNC and CNC aggregates are analyzed. This is followed by a summary of the recent advances in stimuli-accelerated chiral nematic CNC self-assembly procedures, including evaporation-induced self-assembly, continuous coating, vacuum-assisted self-assembly, and shear-induced CNC assembly under confinement. In particular, stimuli-induced unwinding, alignment, and relaxation of chiral nematic structures were highlighted, offering a significant link between the accelerated assembly approaches and uniform chiral nematic nanostructures. Ultimately, future opportunities and challenges for rapid chiral nematic CNC assembly are discussed for more innovative and exciting applications.

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Electric Field‐Driven Control of Cholesteric Cellulose Nanocrystal Orientation and Morphology

Cited by 14 publications

References 46 publications

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Responsive Chiral Photonic Cellulose Nanocrystal Materials

Accelerating Cellulose Nanocrystal Assembly into Chiral Nanostructures

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