Dispersions of multiwalled carbon nanotubes in different nematic mesogens: The study of optical transmittance and electrical conductivity

Lisetski, L. N.; Minenko, S.S.; Fedoryako, A. P.; Lebovka, Nikolaï

doi:10.1016/j.physe.2008.09.004

Cited by 47 publications

(35 citation statements)

References 32 publications

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“…However, the threshold voltage U th was approximately the same for "fresh" suspensions. The changes of relative electrical conductivity '/' o in LC + MWCNT composites evidently reflect the changes of electrical transport through the interfacial nematic layers between different nanotubes [27]. Approximately the same values of U th for pure nematic 5CB and "fresh" sample of 5CB doped by oMWCNTs (0.1% wt) evidence small influence of the networks of nanotubes on the Freedericks transition in interfacial nematic shells, which governs the electric transport.…”

Section: The Responses On the Applied External Electric Fieldmentioning

confidence: 87%

“…The studied dispersion was introduced between the cell walls by the capillary forces; the cell walls were covered by a polyvinyl alcohol film rubbed in one direction as described in literature [27], with the resulting alignment believed to be close to planar.…”

Section: Methodsmentioning

confidence: 99%

“…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: The Responses On the Applied External Electric Fieldmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Section: Incubation Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…However, numerous attempts to reproduce these results in many laboratories did not succeed. No statistically reliable changes in the nematic-isotropic transition temperature T ni for 5CB + MWCNTs suspensions at concentrations up to 0.15 % were observed [110].…”

Section: Phase Transitionsmentioning

confidence: 89%

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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Nanoparticles in Liquid Crystals and Liquid Crystalline Nanoparticles

Stamatoiu

Mirzaei

Feng

et al. 2011

Topics in Current Chemistry

179

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Combinations of liquid crystals and materials with unique features as well as properties at the nanoscale are reviewed. Particular attention is paid to recent developments, i.e., since 2007, in areas ranging from liquid crystal-nanoparticle dispersions to nanomaterials forming liquid crystalline phases after surface modification with mesogenic or promesogenic moieties. Experimental and synthetic approaches are summarized, design strategies compared, and potential as well as existing applications discussed. Finally, a critical outlook into the future of this fascinating field of liquid crystal research is provided.

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Dispersions of multiwalled carbon nanotubes in different nematic mesogens: The study of optical transmittance and electrical conductivity

Cited by 47 publications

References 32 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

Nanoparticles in Liquid Crystals and Liquid Crystalline Nanoparticles

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