Stimuli‐Directed Helical Axis Switching in Chiral Liquid Crystal Nanostructures

Li, Quan

doi:10.1002/9783527807369.ch8

Cited by 9 publications

(3 citation statements)

References 170 publications

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“…Then we express the CLC director n in terms of the polar and the azimuthal angles, θ and φ, as follows n = sin θ cos φ x + sin θ sin φ ŷ + cos θ ẑ, (6) where the angles are functions of z, θ = θ(z) and φ = φ(z), provided invariance with respect to in-plane translations is unbroken. After substituting the director parametrization (6) into Eq.…”

Section: Free Energymentioning

confidence: 99%

“…LCs are known to be responsive materials that are highly sensitive to external stimuli such as electromagnetic fields and boundary (anchoring) conditions. This responsiveness underpins tunability of the helical structures underlying most of the fascinating device applications of CLCs and controllable manipulation of the CLC helical superstructures presents a challenging problem which is of vital importance for both fundamental and technological reasons [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Multiple minimum-energy paths and scenarios of unwinding transitions in chiral nematic liquid crystals

Tenishchev¹,

Kiselev²,

Ivanov³

et al. 2019

Phys. Rev. E

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We apply the minimum energy paths (MEPs) approach to study the helix unwinding transition in chiral nematic liquid crystals. A mechanism of the transition is determined by a MEP passing through a first order saddle point on the free energy surface. The energy difference between the saddle point and the initial state gives the energy barrier of the transition. Two starting approximations for the paths are used to find the MEPs representing different transition scenarios: (a) the director slippage approximation with in-plane helical structures; and (b) the anchoring breaking approximation that involves the structures with profound out-of-plane director deviations. It is shown that, at sufficiently low voltages, the unwinding transition is solely governed by the director slippage mechanism with the planar saddle point structures. When the applied voltage exceeds its critical value below the threshold of the Fréedericksz transition, the additional scenario through the anchoring breaking transitions is found to come into play. For these transitions, the saddle point structure is characterized by out-of-plane deformations localized near the bounding surface. The energy barriers for different paths of transitions are computed as a function of the voltage and the anchoring energy strengths. * tenischev.

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Section: Free Energymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiple minimum-energy paths and scenarios of unwinding transitions in chiral nematic liquid crystals

Tenishchev¹,

Kiselev²,

Ivanov³

et al. 2019

Phys. Rev. E

View full text Add to dashboard Cite

show abstract

“…Tunability of such structures underlies most of the fascinating device applications of CLCs [3,4]. So controllable manipulation of the CLC helical superstructures presents a challenging problem which is of vital importance for both fundamental and technological reasons [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Hysteresis and Freedericksz thresholds for twisted states in chiral nematic liquid crystals: Minimum-energy path approach

Tenishchev¹,

Tambovtcev²,

Kiselev³

et al. 2020

Preprint

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We study minimum-energy pathways (MEPs) between the branches of metastable helical structures in chiral nematic liquid crystals (CNLCs) subjected to the electric field applied across the cell. By performing stability analysis we have found that, for the branches with non-vanishing half-turn number, the threshold (critical) voltage of the Fréedericksz transition is an increasing function of the free twisting wave number. The curves for the threshold voltage depend on the elastic anisotropy and determine the zero-field critical free twisting number where the director out-of-plane fluctuations destabilize the CNLC helix. For each MEP passing through a first order saddle point we have computed the energy barrier as the energy difference between the saddle-point and the initial structures at different values of the applied field. In our calculations, where the initial approximation for a MEP at the next step was determined by the MEP obtained at the previous step, the electric field dependence of the energy barrier is found to exhibit the hysteresis. This is the hysteresis of electrically driven transition of the saddle-point configuration between the planar and the tilted structures involving out-of-plane director deformations. It turned out that, by contrast to the second-order Fréedericksz transition, this transition is first order and we have studied how it depends on the zenithal anchoring energy strength.

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Light‐Driven Self‐Organized Liquid Crystalline Nanostructures Enabled by Chiral Molecular Switches or Motors: From1Dto3DPhotonic Crystals

2018

Photoactive Functional Soft Materials

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Stimuli‐Directed Helical Axis Switching in Chiral Liquid Crystal Nanostructures

Cited by 9 publications

References 170 publications

Multiple minimum-energy paths and scenarios of unwinding transitions in chiral nematic liquid crystals

Multiple minimum-energy paths and scenarios of unwinding transitions in chiral nematic liquid crystals

Hysteresis and Freedericksz thresholds for twisted states in chiral nematic liquid crystals: Minimum-energy path approach

Light‐Driven Self‐Organized Liquid Crystalline Nanostructures Enabled by Chiral Molecular Switches or Motors: From1Dto3DPhotonic Crystals

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