Theoretical study on the effect of electric field for carbon nanotubes dispersed in nematic liquid crystal

Lahiri, T.; Pushkar, S.K.; Poddar, P.

doi:10.1016/j.physb.2020.412177

Cited by 11 publications

(6 citation statements)

References 51 publications

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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%

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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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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“…Here, in equation (6), a p c is the anisotropy in diamagnetic susceptibility for MNPs and it is taken to be positive 0 a p ( ) c > . This term becomes important both for the non-magnetic nanoparticles such as carbon-nanotubes [50], in which case it becomes a dimagnetic contribution and for the goethite MNPs [48]. We retain this term in our free energy profile because it is found that at moderate to high magnetic field regime, this contribution in equation (6) becomes dominant over the contribution resulting from equation (5) [49].…”

Section: Theoretical Modelmentioning

confidence: 99%

“…In this case, we consider the parameter b to be equal to zero i.e. the nanoparticles dispersed in the medium are now non-magnetic in nature and the example for such a nanoparticle is carbon nanotube [50]. Under this condition μ = 0 and equation (32) can be modified as:…”

Section: Case-i: Non-magnetic Nanoparticlesmentioning

confidence: 99%

“…It is evident from equation (51) that bistable coupling between n ˆand m ˆhas no impact on the transition between distorted and saturated states. Bistability becomes relevant only when we consider non-linear terms in equation (50), which is beyond the scope of the present work. Similar to the analysis carried out in section 2.2.1. for non-magnetic nanoparticles, equation (52) gives the threshold for the saturation field h s , which is found to be:…”

Section: Calculation Of Freedericksz Threshold For Transition Between...mentioning

confidence: 99%

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Freedericksz transition in ferronematic liquid crystal under weak anchoring conditions

2021

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Freedericksz effect is investigated theoretically for a ferronematic liquid crystal, which is a colloidal suspension of ferromagnetic nanoparticles in a nematic fluid. Considering a splay type Freedericksz geometry, weak anchoring conditions are assumed at the cell boundaries. The specific nature of this anchoring reveals a rich variety of stable ferronematic phases, which include uniform, distorted and saturated states. Apart from weak anchoring conditions at the cell boundaries, soft planar anchoring is assumed for the mesogenic molecules at the surface of a nanoparticle. The interplay between these two anchoring phenomena along with Frank type elastic theory determine the values of Freedericksz threshold between various ferronematic states. It is found that compared to relatively strong anchoring for the mesogens both at the cell boundaries and at the surface of the nanoparticles, weak anchoring significantly reduces the Freedericksz threshold field. Landau theory is then utilized to understand the nature of transition between different ferronematic states. Based on the phenomenon of segregation effect, these transitions are found to be either first order or second order in nature. The present theory is also extended to non-ferromagnetic nanoparticles and significant reduction in Freedericksz threshold is obtained. Finally, these results are corroborated with experimental findings.

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“…Appropriate NPs could influence the nematic order via different generic mechanisms if inserted into nematic LCs. Important controlling parameters are the concentration of NPs, geometrical shape (Bellini et al, 2000;Kyrou et al, 2018;Kyrou et al, 2020;Skarabot et al, 2022), NP surface treatment (Nobili and Durand, 1992;Lavric et al, 2013a;Oswald and Pieranski, 2019;Kyrou et al, 2020), material characteristics of NPs (Mertelj et al, 2013;Kumar, 2014;Moghadas et al, 2015;Poursamad and Hallaji, 2017;Emdadi et al, 2018a;Emdadi et al, 2018b;Drozd-Rzoska et al, 2019;Jahanbakhsh et al, 2019;Poursamad and Emdadi, 2019;Lahiri et al, 2020;Bury et al, 2022;Ma et al, 2022;Sumandra et al, 2022), andLC material properties (de Gennes, 1995;Kleman and Lavrentovich, 2003;Oswald and Pieranski, 2019). Furthermore, NPs could effectively impose qualitatively different disorders on the LC order (Harris et al, 1973;Cleaver et al, 1996;Crawford and Žumer, 1996;Radzihovsky and Toner, 1997;Popa-Nita and Kralj, 2006).…”

Section: Introductionmentioning

confidence: 99%

Phase behavior of nematic-nanoparticle mixtures

Hölbl

Ranjkesh

Abina

et al. 2023

Front. Soft. Matter

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We study the effects of nanoparticles (NPs) on thermotropic nematic liquid crystals (LCs) in relatively dilute NP–LC mixtures. We are interested in the fundamental generic mechanisms that quantitatively and qualitatively affect the phase behavior of LCs. A simple molecular field analysis shows that a phase transition will likely occur upon entry into the ordered phase. Moreover, the interaction between nematogenic NPs and LCs could force a sergeant–soldier-like behavior, in which only the phase behavior of one component is affected despite the symmetric appearance of the coupling term. When NPs are anisotropic, their influence on LC phase behavior can be qualitatively different depending on the anchoring, even in the absence of the disorder. We illustrate numerically that a random-field-type disorder might impose either short-range, quasi-long-range, or even long-range order, which might survive.

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Theoretical study on the effect of electric field for carbon nanotubes dispersed in nematic liquid crystal

Cited by 11 publications

References 51 publications

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

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

Freedericksz transition in ferronematic liquid crystal under weak anchoring conditions

Phase behavior of nematic-nanoparticle mixtures

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