Chiral nematic droplets with tangential anchoring and negative dielectric anisotropy in an electric field

Bajc, J.; Bezić, J.; Žumer, S.

doi:10.1103/physreve.51.2176

Cited by 24 publications

(12 citation statements)

References 18 publications

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“…Chiral nematic droplets have been studied extensively: their formation in polymerdispersed LC [69], the stablity of structures [6,7,96,[99][100][101][102][103][104][105], structural transitions between them [106], influence of external fields on the structure [99,105,[107][108][109], insertion of fibers [110] and assembly of nanoparticles in surface or bulk defects [111][112][113].…”

Section: Chiral Nematic Dropletsmentioning

confidence: 99%

“…Eden izmed topološko bolj pestrih sistemov so kiralni nematski tekoči kristali ali holesteriki, v katerih se direktor v prostoru vrti okoli smeri, ki je pravokotna nanj. V neograjenih vzorcih je njihovo najnižje energijsko stanje slojevita struktura, v kateri se direktor vrti okoli osi, ki je pravokotna na holesterične sloje.Če se kiralni nematik nahaja v omejenem prostoru, v katerem se robni pogoj ne ujema s plastovito holesterično strukturo, je njegovo ureditev frustrirana, zaradičesar se pojavijoštevilna topološko raznolika stanja, kot so na primer različni tipi skyrmionskih in hopfionskih kvazidelcev v homeotropnih celicah [2][3][4][5][62][63][64]170] ter različne plastovite strukture v planarnih kiralnih nematskih kapljicah [96,[99][100][101][102][103][104][105][106][107][108][109][111][112][113].…”

Section: Razširjeni Slovenski Pregled Uvodunclassified

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Topological Formations in Chiral Nematic Droplets

Posnjak¹

2018

Springer Theses

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Section: Chiral Nematic Dropletsmentioning

confidence: 99%

Section: Razširjeni Slovenski Pregled Uvodunclassified

Topological Formations in Chiral Nematic Droplets

Posnjak¹

2018

Springer Theses

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“…Simulations of chiral LCs in channels have shown that their defect structure can be manipulated through confinement, thereby raising intriguing prospects for technology (32)(33)(34)(35). Chiral LC droplets have also been studied both numerically (36)(37)(38) and experimentally (39,40). More recent, intriguing simulations of planar chiral droplets with strong anchoring by Seč et al (41) have examined their phase behavior as a function of chirality.…”

mentioning

confidence: 99%

Blue-phase liquid crystal droplets

Martínez‐González

Zhou

Rahimi

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Blue phases of liquid crystals represent unique ordered states of matter in which arrays of defects are organized into striking patterns. Most studies of blue phases to date have focused on bulk properties. In this work, we present a systematic study of blue phases confined into spherical droplets. It is found that, in addition to the so-called blue phases I and II, several new morphologies arise under confinement, with a complexity that increases with the chirality of the medium and with a nature that can be altered by surface anchoring. Through a combination of simulations and experiments, it is also found that one can control the wavelength at which blue-phase droplets absorb light by manipulating either their size or the strength of the anchoring, thereby providing a liquid-state analog of nanoparticles, where dimensions are used to control absorbance or emission. The results presented in this work also suggest that there are conditions where confinement increases the range of stability of blue phases, thereby providing intriguing prospects for applications.blue phases | chiral liquid crystals | droplets | confinement B lue phases of liquid crystals (LCs) are characterized by a local director field that forms double-twisted cylinders, arranged into defect regions that are periodically repeated in space (1, 2). The symmetry properties of blue phases (BPs) have attracted considerable attention, as have their potential applications in a wide range of technologies (3-7). Theoretical and computational studies of the bulk structure and dynamics of BPs have helped elucidate their nature (1, 8, 9-15) in considerable detail. In the bulk, however, BPs are only found in a narrow range of temperature, between the cholesteric and the isotropic phases (1-6, 10-18), thereby placing limits on their practical utility. Recent efforts have therefore focused on increasing their stability over wider ranges of temperature and chirality, for example through addition of nanoparticles (19, 20, 21-23), polymers (24-26), or by manipulating their flexoelectricity (14).Confined chiral liquid crystals are of interest for applications in optical devices (27)(28)(29)(30)(31). Simulations of chiral LCs in channels have shown that their defect structure can be manipulated through confinement, thereby raising intriguing prospects for technology (32)(33)(34)(35). Chiral LC droplets have also been studied both numerically (36-38) and experimentally (39,40). More recent, intriguing simulations of planar chiral droplets with strong anchoring by Seč et al. (41) have examined their phase behavior as a function of chirality. In particular, it was reported that the twist bipolar structure (BS) is stable in the low chirality regime, whereas the radial spherical structure (RSS) is preferred at high chirality. The BS state has a cylindrical symmetry, where the director field is uniform along the symmetry axis of the droplet and rotates in the perpendicular direction forming bent cholesteric layers. In the RSS state, the director field also forms curved ...

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“…Previous theoretical (30)(31)(32) and experimental (33, 34) studies of CLC droplets revealed the existence of two main director configurations, whose stability depends on the R/p i ratio, where R is the radius of the droplet and p i the intrinsic pitch. Xu and Crooker (34) showed that for p i > R, CLC droplets adopt a so-called twisted bipolar structure (TBS), characterized by two diametrically opposite surface defects (boojums).…”

Section: Significancementioning

confidence: 97%

Light-activated helical inversion in cholesteric liquid crystal microdroplets

Ślęczkowski

Zhou

Iamsaard

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Cholesteric liquid crystal (CLC) droplets exhibit nontrivial topological features, which are controlled by the ratio between the cholesteric pitch and the droplet radius. The radial spherical structure (RSS) is of particular interest, as it reveals an onion-like concentric organization of the cholesteric helices, leading to the expression of spherical Bragg microcavities. Using an overcrowded alkene-based unidirectional molecular motor as a dopant, we show that the topological defect structure in the droplet can be activated by illumination. By using appropriate molecular motor concentrations, light can either break the symmetry of topological defects (as observed for the bent-twisted bipolar structure), or it can induce inversion of handedness in an onion-like organization (in the case of RSS). This latter feature may pave the way toward alternative activation modes of lasers based on cholesteric droplets. By also studying CLC droplets once they have reached full photoconversion at photostationary state (PSS), we highlight that the strong influence of confinement on the droplets structure occurs to the same extent after the helix inversion event. Our results are interpreted in terms of numerical simulations of the droplets' structure, which shed light on the major role played by curvature close to the droplets' center, this latter one becoming dominant when the droplet radius is small.

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Chiral nematic droplets with tangential anchoring and negative dielectric anisotropy in an electric field

Cited by 24 publications

References 18 publications

Topological Formations in Chiral Nematic Droplets

Topological Formations in Chiral Nematic Droplets

Blue-phase liquid crystal droplets

Light-activated helical inversion in cholesteric liquid crystal microdroplets

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