The induction of the N<sub>tb</sub>phase in mixtures

Ramou, Efthymia; Welch, Chris; Hussey, James R.; Ahmed, Ziauddin; Karahaliou, P. K.; Mehl, Georg H.

doi:10.1080/02678292.2018.1524523

Cited by 14 publications

(14 citation statements)

References 52 publications

(55 reference statements)

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“…Finally, it should be noted that breaking one (or more) of the symmetries of the N phase (nonchirality, uniaxiality, a‐polarity) can lead to a variety of more highly ordered nematic phases. such as i) the chiral nematic phase (discussed below), ii) biaxial nematic phases, [ 65,66 ] which are defined by two directors perpendicular to each other and have been identified experimentally in colloidal board‐like systems, [ 67,68 ] a ternary lyotropic system that formed board‐like micelles [ 69 ] and in thermotropic banana‐shaped systems, [ 70 ] iii) the nematic twist‐bend [ 61,71–76 ] a chiral phase formed by achiral mesogens, characterized by a helical modulation of the orientational order with a pitch of the order of 10 nm.…”

Section: The Liquid Crystalline Statementioning

confidence: 99%

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Esteves

Ramou

Porteira

et al. 2020

Advanced Optical Materials

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Fast, real‐time detection of gases and volatile organic compounds (VOCs) is an emerging research field relevant to most aspects of modern society, from households to health facilities, industrial units, and military environments. Sensor features such as high sensitivity, selectivity, fast response, and low energy consumption are essential. Liquid crystal (LC)‐based sensors fulfill these requirements due to their chemical diversity, inherent self‐assembly potential, and reversible molecular order, resulting in tunable stimuli‐responsive soft materials. Sensing platforms utilizing thermotropic uniaxial systems—nematic and smectic—that exploit not only interfacial phenomena, but also changes in the LC bulk, are demonstrated. Special focus is given to the different interaction mechanisms and tuned selectivity toward gas and VOC analytes. Furthermore, the different experimental methods used to transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends in the field, in particular the opportunities for LC‐based advanced materials in artificial olfaction, are also discussed.

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Section: The Liquid Crystalline Statementioning

confidence: 99%

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Esteves

Ramou

Porteira

et al. 2020

Advanced Optical Materials

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“…Ramou et al. reported that the N TB phase can be induced in mixtures of conventional nematic and nonmesogenic dimers . Besides liquid‐crystal dimers, the N TB phase has also been observed in bent‐core molecules, oligomers, and polymers .…”

Section: Introductionmentioning

confidence: 99%

“…[16] Ramou et al reported that the N TB phase can be induced in mixtures of conventionaln ematic and nonmesogenic dimers. [17] Besides liquid-crystal dimers, the N TB phase has also been observedi nb ent-core molecules, [5,[18][19][20] oligomers, [21][22][23][24][25] and polymers. [3,4,26] Although the majority of twist-bend nematogens developeds of ar are achiral,t here have been af ew reports on formation of the N TB phase based on chiral bentshaped molecules,i nw hicht he chirality is located in the mesogenic-arm core, [27,28] terminal chain, [29] or spacer.…”

Section: Introductionmentioning

confidence: 99%

Ether‐ and Thioether‐Linked Naphthalene‐Based Liquid‐Crystal Dimers: Influence of Chalcogen Linkage and Mesogenic‐Arm Symmetry on the Incidence and Stability of the Twist–Bend Nematic Phase

Arakawa

Ishida

Tsuji

2020

Chemistry A European J

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The twist–bend nematic (NTB) phase with a heliconical nanostructure of the local director generating symmetry breaking by achiral bent‐shaped molecules is a hot topic of current liquid‐crystal science. As opposed to the most common methylene‐linked dimers, this study demonstrates chalcogen ether‐ and/or thioether‐linked 6‐(4‐cyanophenyl)‐2‐naphthyl‐based liquid‐crystal dimers with symmetric and asymmetric π‐conjugated mesogenic‐arm structures that exhibit the NTB phase. Although the symmetric bis(ether)‐linked dimer exhibits only the conventional nematic (N) phase, the asymmetric bis(ether)‐linked dimer can form the NTB phase. All thioether‐linked dimers form the NTB phase, wherein the dimers with asymmetric arms vitrify in the NTB phase on cooling to room temperature. The phase transitions are discussed in terms of the chalcogen linkage combination, mesogenic‐arm symmetry, and spacer length. It is revealed that thioether‐linked dimers based on asymmetric π‐conjugated mesogenic arms with terminal cyano groups are highly beneficial for the realization of materials that form a wide range of NTB phases and glassy NTB states at room temperature.

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“…We therefore sought a new method to obtain splay nematic materials; induction of the NS phase in mixtures of two materials that do not exhibit this phase, in a similar vein to the induction of the twist-bend nematic phase in binary mixtures. [19][20][21]…”

Section: Introductionmentioning

confidence: 99%