Relaxation phenomena in nematic liquid crystals with multiwall carbon nanotubes adding

Cîrtoaje, Cristina; Stoian, Victor; Petrescu, Emil; Motoc, Cornelia

doi:10.1117/12.2178333

Cited by 4 publications

(4 citation statements)

References 7 publications

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“…However, homeotropic coupling is also possible [17]. Thus, for suspensions of CNTs based on LC with positive diamagnetic susceptibility anisotropies, one should expect decreasing of the threshold field of the magnetic Fréedericksz transition, which is confirmed by experiment [18–19], as well as a decrease in the electric field of the Fréedericksz transition [11,14,20–22]. Along with this, there are experimental studies devoted to the investigation of LC suspensions with CNTs functionalized by ferromagnetic particles [19,23–25], where an enhanced magneto-optical response is also observed in comparison with a pure LC.…”

Section: Introductionmentioning

confidence: 90%

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

Petrov¹,

Skokov²,

Zakhlevnykh³

2017

Beilstein J. Nanotechnol.

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We propose a continuum theory of orientational phase transitions induced by an external magnetic field in a suspension of carbon nanotubes in a nematic liquid crystal. It is shown that in a magnetic field a non-uniform and two different uniform phases are possible in the suspension. The uniform phases of the suspension differ by the type of orientational coupling of nanotubes with the liquid crystal matrix (the planar type when the nanotubes are oriented along the matrix director, and the homeotropic type when the nanotubes are perpendicular to the director). The possibility of a redistribution of the nanotube concentration (segregation effect) is shown. The fields of orientational transitions between uniform and non-uniform phases of the suspension are found analytically. It is shown that, when the nanotubes are weakly coupled to the matrix, the magnetic field induces reentrant transitions (uniform planar phase–non-uniform phase–uniform homeotropic phase–non-uniform phase). These transitions can be of first or of second order depending on the carbon nanotubes segregation intensity.

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Section: Introductionmentioning

confidence: 90%

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

Petrov¹,

Skokov²,

Zakhlevnykh³

2017

Beilstein J. Nanotechnol.

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“…The effects of applied electric fields on the alignment of CNTs in LCs have been intensively discussed in many recent theoretical and experimental studies [122][123][124][125][126][127][128][129][130][131].…”

Section: Nematic Liquid Crystalsmentioning

confidence: 99%

“…The dynamic behavior of CNT-nematic LC composites in the electric and magnetic fields has been analyzed both theoretically and experimentally [124,[127][128][129][130][131]. A theoretical model based on elastic continuum theory allowed the evaluation of the relaxation times [124].…”

Section: Nematic Liquid Crystalsmentioning

confidence: 99%

Effects of Dispersed Carbon Nanotubes and Emerging Supramolecular Structures on Phase Transitions in Liquid Crystals: Physico-Chemical Aspects

Lisetski

Bulavin

Lebovka

2023

Liquids

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The current state of the study of different liquid crystalline (LC) systems doped with carbon nanotubes (CNTs) is discussed. An attempt is endeavored to outline the state-of-the-art technology that has emerged after two past decades. Systematization and analysis are presented for the integration of single- and multi-walled carbon nanotubes in thermotropic (nematic, smectic, cholesteric, ferroelectric, etc.) and lyotropic LCs. Special attention is paid to the effects of alignment and supramolecular organization resulting from orientational coupling between CNTs and the LC matrix. The effects of the specific inter-molecular and inter-particle interactions and intriguing microstructural, electromagnetic, percolation, optical, and electro-optical properties are also discussed.

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“…In the majority of experimental publications [7,16,24–26] the planar type of anchoring between the nanotubes and the LC matrix is noted. For CNT suspensions based on nematic liquid crystals (NLCs) with positive anisotropy of the diamagnetic susceptibility, this leads to a decrease in the critical fields of magnetic [27–28] and electric [14,16,26,29–30] Fréedericksz transition (a threshold process of changing the orientational structure inside an NLC layer under the action of external fields [31]). Experiments show [28,32–34] that in nematic liquid crystal–carbon nanotube (NLC-CNT) mixtures additionally functionalized with ferromagnetic particles, the magneto-optical response increases in comparison with pure LC.…”

Section: Introductionmentioning

confidence: 99%

Magnetic segregation effect in liquid crystals doped with carbon nanotubes

Petrov

Skokov

Zakhlevnykh

et al. 2019

Beilstein J. Nanotechnol.

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We study the orientational transitions in a suspension of carbon nanotubes in a nematic liquid crystal induced by an external magnetic field. The case of a finite orientational anchoring of liquid crystal molecules at the surface of doped carbon nanotubes is considered. It is shown that in a magnetic field the initial homogeneous planar texture of the liquid crystal–carbon nanotubes mixture is disturbed in a threshold manner (Fréedericksz transition). The orientational and concentration distributions of the suspension are studied for different values of the magnetic field strength and segregation intensity of the impurity subsystem. The optical phase lag between ordinary and extraordinary rays of light transmitted through a layer of a liquid crystal composite is calculated. The possibility of changing the nature of the Fréedericksz transition from second order to first order is shown. This tricritical behavior is related to the redistribution of the carbon nanotubes (segregation effect) inside the layer.

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Relaxation phenomena in nematic liquid crystals with multiwall carbon nanotubes adding

Cited by 4 publications

References 7 publications

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

Effects of Dispersed Carbon Nanotubes and Emerging Supramolecular Structures on Phase Transitions in Liquid Crystals: Physico-Chemical Aspects

Magnetic segregation effect in liquid crystals doped with carbon nanotubes

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