Optical Transmission and Conductivity of Nematic Liquid Crystals Containing Dispersed Multiwall Nanotubes

Lysetskiy, L.; Panikarskaya, V. D.; Sidletskiy, O.; Kasian, N. A.; Kositsyn, S.; Shtifanyuk, P. P.; Lebovka, Nikolaï; Lisunova, Milana; Melezhyk, O.V.

doi:10.1080/15421400701681315

Cited by 17 publications

(14 citation statements)

References 15 publications

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“…An increasing ÁTr is a rather typical phenomenon for liquid crystals filled with MWCNTs [25,27,50]. Note that doping of 5CB by o-MWCNTs resulted in evident increase of ÁTr value, while time incubation resulted in decrease of ÁTr.…”

Section: Incubation Processesmentioning

confidence: 99%

“…Furthermore calculations of interactions between CNT and LC molecules were performed using quantum chemistry [21] and molecular dynamics with Lennard-Jones type atom-atom potentials [22], as well as semi-phenomenological approaches relating orientational order parameter of the nematic matrix and dispersed CNTs [23,24]. Among experimental data on LC + CNT dispersions, one should note a concept of "percolation"-type behavior describing concentration dependence of electric conductivity [25], as well as data on optical transmittance, Raman scattering, and electro-optic effects typical for nematics obtained in different LC matrices [26,27]. The presence of CNTs perturbs the local ordering of a LC and results in formation of complex textures that can be detected by optical microscopy studies.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and incubation processes in composite liquid crystalline material (5CB) filled with multi walled carbon nanotubes

Lisetski

Minenko

Ponevchinsky

et al. 2011

Materialwissenschaft Werkst

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This work reports a study on microstructure, electrical conductivity and phase transitions of 5CB(4-pentyl-49-cyanobiphenyl) + multi-walled carbon nanotubes (MWCNTs) composite materials. The concentration of MWCNTs was varied within 0.025 and 1 wt.%. The unmodified (o) and modified (m) MWCNTs were used. The mild milling was applied for shortening length of MWCNTs. Direct microscopic observation of composites at different concentrations C of MWCNTs evidenced the presence of aggregation and percolation processes. Formation of percolation networks was observed at C p L 0.025 -0.05% wt and C=C p L 0.1 -0.25% wt for o-MWCNTs and m-MWCNTs composites, respectively. Increase of the percolation threshold for m-MWCNTs, possibly, reflected their smaller aspect ratio r. The conductivity exponents were approximately the same (t L 3.3 l 0.1) for both o-MWCNTs and m-MWCNTs. The microstructure of MWCNT aggregates was not stable in time. The initially formed loose aggregates (L-aggregates) transformed into the more compact C-aggregates during the incubation time of one week. The incubation resulted in decrease of anisotropy, change in phase behaviour near the nematic-isotropic transition, and influenced external electric field response of the studied composite material. Inkubation führt zu einer Abnahme der Anisotropie, einem Wechsel der Phase in der Nähe der nematischen-isotropen Umwandlung und beeinflusst die Antwort auf ein externes elektrisches Feld der studierten Kompositmaterialien.

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Section: Incubation Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure and incubation processes in composite liquid crystalline material (5CB) filled with multi walled carbon nanotubes

Lisetski

Minenko

Ponevchinsky

et al. 2011

Materialwissenschaft Werkst

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“…Such behaviour was typical for LC matrices doped with CNTs [143,172]. The cut-off wavelength can slightly change if we pass from cyanobiphenyl 5CB to nematics of different chemical nature.…”

Section: Optical Transmissionmentioning

confidence: 93%

“…Experimental studies of these effects were discussed in details [13,111,124,125,140,143]. Figure 10.14 shows the typical curves of electrical conductivity σ as a function of concentration of MWCNTs, C, in EBBA [111] and 5CB [124] obtained at the fixed temperatures that were just above the solid-to-nematic phase transition temperatures.…”

Section: Electrical Conductivitymentioning

confidence: 99%

“…Hence, the nature of incubation can reflect the aggregation caused by Brownian motion of MWCNTs. Many experimental data for nematics filled by CNTs evidenced in favor of the percolation mechanism of electrical conductivity [13,111,124,125,140,143]. The percolation is accompanied by the abrupt changes in different physical properties of LC + CNT composite, and this transition may be identified as a geometrical phase transition related with formation of the spanning network of CNTs [144][145][146][147].…”

Section: Aggregation and Incubationmentioning

confidence: 99%

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Carbon Nanotubes in Liquid Crystals: Fundamental Properties and Applications

Lisetski

Soskin

Lebovka

2015

Springer Proceedings in Physics

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The structure and properties of liquid crystalline suspensions filled by carbon nanotubes (CNTs) are critically reviewed. Special attention is paid to interactions between CNTs and molecules of the liquid crystals (LC), which lead to formation of ordered supramolecular structures. These structures, in turn, determine unique physical properties of LC + CNT suspensions, including electrical conductivity, dielectric permittivity, phase transitions, optical transmission, memory effects that can be used in electrooptic and optoelectronic devices, etc. Great variety of LC phases are considered as a host media, such as nematics, cholesterics, smectics of different types (including ferroelectrics), lyotropic, chromonic, ionic and hydrogen-bonded liquid crystals. Alongside multi-and single-walled carbon nanotubes, the suspensions can also contain the platelets of organoclays used for facilitation of CNT dispersing. Recent practical applications of LC + CNT suspensions and nanomaterials based thereon are also outlined.

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Comparative Investigations of Light Transmission in Aligned and Non-aligned Textures of Homogeneous Mixtures of 4-n-alkyl-4′-Cyanibiphenyl Mesogens at Direct and Reverse smectic A ↔ isotropic liquid Phase Transitions

Nesrullajev

2017

Braz J Phys

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Optical Transmission and Conductivity of Nematic Liquid Crystals Containing Dispersed Multiwall Nanotubes

Cited by 17 publications

References 15 publications

Microstructure and incubation processes in composite liquid crystalline material (5CB) filled with multi walled carbon nanotubes

Microstructure and incubation processes in composite liquid crystalline material (5CB) filled with multi walled carbon nanotubes

Carbon Nanotubes in Liquid Crystals: Fundamental Properties and Applications

Comparative Investigations of Light Transmission in Aligned and Non-aligned Textures of Homogeneous Mixtures of 4-n-alkyl-4′-Cyanibiphenyl Mesogens at Direct and Reverse smectic A ↔ isotropic liquid Phase Transitions

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