Nanoparticles: Additives and Building Blocks for Liquid Crystal Phases

Umadevi, S.; Ganesh, V.; Hegmann, Torsten

doi:10.1002/9783527671403.hlc089

Cited by 8 publications

(7 citation statements)

References 267 publications

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“…I pump is the combined intensity of the pump beams throughout the cell and is attenuated as shown in Eq. (1). Finally x and z are distances along the intensity grating and into the cell respectively as indicated in Fig.…”

Section: Heating Model and Comparison To Experimentsmentioning

confidence: 99%

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Gold nanoparticle liquid crystal composites as a tunable nonlinear medium

2014

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We investigate the nonlinearity of a liquid crystal cell doped with gold nanoparticles by considering their selective absorption. Such nonlinearities are promising for optical processing applications and optical limiters. Systems displaying thermal nonlinearities are particularly attractive as the maximum nonlinearity may occur in the absence of an applied field and additionally this nonlinearity can be controlled by the reorientation of the liquid crystal. We show that there exists a theoretical optimum concentration of absorbers, which maximizes the nonlinearity. Further we show that the nonlinearity of the system can be tuned by the reorientation of the liquid crystal host, with the nonlinearity decreasing from 9×10 −5 cm 2 W −1 to zero by the application of a magnetic field of the order of 0.01 Tesla. This allows a fine control of the diffraction efficiency and, in principle, many other nonlinear effects.

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Section: Heating Model and Comparison To Experimentsmentioning

confidence: 99%

“…The doping of liquid crystals (LCs) with nanoparticles has become a common method of improving their optical, magnetic, electrical and physical properties [1]. For example, ferroelectric nanoparticles have been shown to decrease the Fréedericksz threshold and increase the birefringence of nematics [2,3].…”

Section: Introductionmentioning

confidence: 99%

Gold nanoparticle liquid crystal composites as a tunable nonlinear medium

2014

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“…Gold colloids have been previously generated through photo‐irradiation or microwave induced nucleation of nanoparticles from a solution of gold precursor in Triton X‐100, however these studies have been limited to spherical nanoparticles. More recently, branched nanoparticles with well‐defined tips have been reported to be synthesized in this surfactant using both seeded and nonseeded approaches. In the seeded method, star‐shaped nanoparticles with regular branches can be produced under certain conditions.…”

Section: Introductionmentioning

confidence: 99%

“…For the nonseeded approach, a very high concentration of the surfactant was applied in order to operate in a liquid crystal regime. This allowed production of gold nanoparticles with long thorns but highly irregular structures …”

Section: Introductionmentioning

confidence: 99%

Simple and Rapid High-Yield Synthesis and Size Sorting of Multibranched Hollow Gold Nanoparticles with Highly Tunable NIR Plasmon Resonances

Blanch

Döblinger

Rodrı́guez-Fernández

2015

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Branched gold nanoparticles with sharp tips are considered excellent candidates for sensing and field enhancement applications. Here, a rapid and simple synthesis strategy is presented that generates highly branched gold nanoparticles with hollow cores and a ca.100% yield through a simple one-pot seedless reaction at room temperature in the presence of Triton X-100. It is shown that multibranched hollow gold nanoparticles of tunable dimensions, branch density and branch length can be obtained by adjusting the concentrations of the reactants. Insights into the formation mechanism point toward an aggregative type of growth involving hollow core formation first, and branching thereafter. The pronounced near-infrared (NIR) plasmon band of the nanoparticles is due to the combined contribution from hollowness and branching, and can be tuned over a wide range (≈700-2000 nm). It is also demonstrated that the high environmental sensitivity of colloidal dispersions based on multibranched hollow gold nanoparticles can be boosted even further by separating the nanoparticles into fractions of given sizes and improved monodispersity by means of a glycerol density gradient. The possibility to obtain highly monodisperse multibranched hollow gold nanoparticles with predictable dimensions (50-300 nm) and branching and, therefore, tailored NIR plasmonic properties, highlights their potential for theranostic applications.

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“…К та-ким средам относятся, например, жидкие кристаллы [2,3] и блок-сополимеры [4]. Локализация квантовых точек (КТ) в ряде систем контролируется взаимодей-ствием, обусловленным образованием ионных связей, между поверхностями квантовых точек и функцио-нальными группами анизотропных молекул [5].…”

Section: Introductionunclassified