(E,T) Phase Diagrams in Polar Compounds

Manai, M.; Gharbi, A.; Essid, S.; Achard, M. F.; Marcerou, J. P.; Nguyen, H. T.; Rouillon, J. C.

doi:10.1080/00150190600961988

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…This is in line with the presence of only short range order, as typical for isotropic liquids with a locally ordered cluster structure (cybotaxis) 126,127 and for percolated liquids 128 often occurring besides frustrated LC phases (blue phases, Twist Grain Boundary phases, SmQ phases, etc.). 129130,131,132,133,134 As shown in Fig. 14 for compound 10, as example, the change of the line width of the XRD small angle scattering at the Iso-Iso1 transition is continuous without any distinct jump, as also found for the Iso-Iso1 [ * ] -transitions.…”

Section: Cubic and Non-cubic 3d Phases Of Compounds 7-12supporting

confidence: 55%

Y-shaped tricatenar azobenzenes – functional liquid crystals with synclinic–anticlinic transitions and spontaneous helix formation

et al. 2020

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Section: Cubic and Non-cubic 3d Phases Of Compounds 7-12supporting

confidence: 55%

Y-shaped tricatenar azobenzenes – functional liquid crystals with synclinic–anticlinic transitions and spontaneous helix formation

et al. 2020

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“…The diagram obtained with γ = 0.2 is chosen to illustrate qualitatively (figure 3) the sequences of phases which appear for the two compounds we have studied experimentally in our group : the C10F3 and the C7F2 [6,28,29,30].…”

Section: A Computation Of Phase Diagramsmentioning

confidence: 99%

Extension of the Hamaneh-Taylor model using the macroscopic polarization for the description of chiral smectic liquid crystals

et al. 2009

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Chiral smectic liquid crystals exhibit a series of phases, including ferroelectric, antiferroelectric, and ferrielectric commensurate structures as well as an incommensurate Sm-Calpha* phase. We carried out an extension of the phenomenological model recently presented by Hamaneh and Taylor based on the distorted-clock model. The salient feature of this model is that it links the appearance of phases to a spontaneous microscopic twist: i.e., an increment alpha of the azimuthal angle from layer to layer. The balance between this twist and an orientational order parameter J gives the effective phase. We introduce a second orientational order parameter I , which physical meaning comes from the macroscopic polarization; the effect of an applied electric is also studied. We derive phase diagrams and correlate them to our experimental results under field showing the sequence of phases versus temperature and electric field in some compounds.

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“…1 Helical and polar structures have been known to appear as a result of a chiral effect: 2 the helical structures are observed in the chiral nematic, blue, and twist grain boundary liquid crystal phases, and the polar structures, with the helical structures in some cases, observed in the ferroelectric, antiferroelectric, and related chiral liquid crystal phases. In our previous studies, a dichiral azobenzene compound (AZO-PP, Figure 1) was designed and prepared, 3,4 and was found to exhibit two SmQ [5][6][7][8][9][10][11] phases that are known to possess three-dimensional (3D) tetragonal liquid crystal structures. 5,6 In this Letter, on the basis of the detailed investigation on the effect of the optical purity of AZO-PP, a new type of chiral effect that induces the optical anisotropy in the 3D liquid crystal phase is for the first time reported.…”

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Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

et al. 2009

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The effect of chirality on the liquid crystal organization has been systematically investigated between (S,S)- and (R,R)-isomers of a dichiral azobenzene compound. The racemic mixture was found to show the cubic phase (Im3m), indicating that the studied compound shows the cubic structure without the effect of chirality. However, with increasing optical purity of the racemic mixture, the cubic (Im3m) structure changes into the tetragonal phases (I422 and I4(1)22), which have been known as the SmQ phases, via a chiral cubic phase (I432). This is the first example of "chirality-driven" cubic-tetragonal structural change observed in liquid crystal systems, which is experimental evidence showing the novel type of chiral effect that produces the anisotropy in the structures of soft materials. The emergence of the anisotropy, i.e., the cubic-tetragonal phase transformation, is also induced by means of photoinduced phase transition of the SmQ phases based on cis-trans photoisomerization of the azobenzene compounds.

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(E,T) Phase Diagrams in Polar Compounds

Cited by 12 publications

References 8 publications

Y-shaped tricatenar azobenzenes – functional liquid crystals with synclinic–anticlinic transitions and spontaneous helix formation

Y-shaped tricatenar azobenzenes – functional liquid crystals with synclinic–anticlinic transitions and spontaneous helix formation

Extension of the Hamaneh-Taylor model using the macroscopic polarization for the description of chiral smectic liquid crystals

Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

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