Detection of graphene chirality using achiral liquid crystalline platforms

Basu, Rajratan; Kinnamon, Daniel; Garvey, Alfred

doi:10.1063/1.4931147

Cited by 15 publications

(14 citation statements)

References 37 publications

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“…Sample preparations and experimental details are mentioned elsewhere. [32] As expected, 9OO4 in the absence of GP does not exhibit any electroclinic effect in the smectic-A phase, confirming the absence of molecular chirality associated with pure 9OO4. On the other hand, the GP-doped 9OO4 clearly shows a bulk electroclinic effect that grows on cooling towards T AC Ã, demonstrating a net chirality in the smectic-A phase.…”

Section: Detection Of Graphene Strain Chirality Using Lcssupporting

confidence: 76%

“…It is also important to point out that the magnitude of e c observed in this experiment is a few orders of magnitude smaller than that of the fully chiral LCs, [48] indicating weak chirality at graphene surface. [32] Due to the chiral induction by graphene flakes, the director in the nematic phase of 5CB undergoes a helical twist with a pitch length P, where P is the distance over which the director rotates by an angle of 2π. LC 5CB is used for this twist experiment because of its availability with a room temperature nematic phase.…”

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%

“…LC 5CB is used for this twist experiment because of its availability with a room temperature nematic phase. LC cells with a 90°twist [32] have been used in this experiment. A uniform cell thickness was maintained by randomly dispersed 6.8-μm spacer particles during the fabrication of the cells.…”

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%

“…This large P indicates that the graphene-induced chirality is weakthis is consistent with weak electroclinic signal for the 9OO4 + GP sample. [32] …”

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%

“…We will present that (a) the hexagonal graphene nanostructure can impose planar alignment onto the nematic and smectic phases of the LC; (b) monolayer graphene flakes can enhance the orientational order parameter, showing an enhancement in the dielectric anisotropy in the nematic phase; [29] (c) the presence of graphene flakes can accelerate the electro-optic response in a nematic LC; [30] (d) graphene flakes can be used to enhance the tilted smectic-C Ã order, giving rise to a faster ferroelectric switching response in the LC [31] and finally, (e) the strain chirality of the graphene surface can propagate into the LC, exhibiting an electroclinic effect in the smectic-A phase and a macroscopic helical twist of the LC director in the nematic phase. [32] …”

Section: Introductionmentioning

confidence: 97%

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Graphene and liquid crystal mediated interactions

2016

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The two-dimensional graphene-honeycomb structure can interact with the liquid crystal's (LC) benzene rings through π-π electron stacking. This LC-graphene interaction gives rise to a number of interesting physical and optical phenomena in the LC. In this paper, we present a combination of a review and original research of the exploration of novel themes of LC ordering at the nanoscale graphene surface and its macroscopic effects on the LC's nematic and smectic phases. We show that monolayer graphene films impose planar alignment on the LC, creating pseudo-nematic domains (PNDs) at the surface of graphene. In a graphenenematic suspension, these PNDs enhance the orientational order parameter, exhibiting a giant enhancement in the dielectric anisotropy of the LC. These anisotropic domains interact with the external electric field, resulting in a non-zero dielectric anisotropy in the isotropic phase as well. We also show that graphene flakes in an LC reduce the free ion concentration in the nematic media by an ion-trapping process. The reduction of mobile ions in the LC is found to have subsequent impacts on the LC's rotational viscosity, allowing the nematic director to respond quicker on switching the electric field on and off. In a ferroelectric LC (smectic-C Ã phase), suspended graphene flakes enhance the spontaneous polarisation by improving the tilted smectic-C Ã ordering resulting from the π-π electron stacking. This effect accelerates the ferroelectric-switching phenomenon. Graphene can possess strain chirality due to a soft shear mode. This surface chirality of graphene can be transmitted into LC molecules exhibiting two types of chiral signatures in the LCs: an electroclinic effect (a polar tilt of the LC director perpendicular to, and linear in, an applied electric field) in the smectic-A phase, and a macroscopic helical twist of the LC director in the nematic phase. Finally, we show that a graphene-based LC cell can be fabricated without using any aligning layers and ITO electrodes. Graphene itself can be used as the electrodes as well as the aligning layers, obtaining an electro-optic effect of the LC inside the cell. P A 50 m P A Planar alignment 0 V 45 V Homeotropic alignment E ARTICLE HISTORY

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Section: Detection Of Graphene Strain Chirality Using Lcssupporting

confidence: 76%

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%

“…This large P indicates that the graphene-induced chirality is weakthis is consistent with weak electroclinic signal for the 9OO4 + GP sample. [32] …”

Section: Detection Of Graphene Strain Chirality Using Lcsmentioning

confidence: 99%