Role of anchoring on the typical textures of the NTB phase - Laboratoire Charles Coulomb (L2C) Accéder directement au contenu
Poster De Conférence Année : 2019

Role of anchoring on the typical textures of the NTB phase

Alaya Soumaya
  • Fonction : Auteur
Abir Aouini
  • Fonction : Auteur correspondant
  • PersonId : 1039503

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Maurizio Nobili
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  • PersonId : 1016764
Ivan Dozov
Daniel Stoenescu
Christophe Blanc

Résumé

Heliconal nematic twist bend (NTB) phases are usually not well oriented in planar commercial cells, even in thin (~1 µm) ones where a micron-sized periodic texture is usually observed [1,2,3] (see Fig.1-a). The origin of the stripe patterns is attributed to the rapid shrinking of the pseudo-layers below the N-NTB phase transition temperature, which yields an undulation instability. The observed periodicity is found to be twice the cell gap [1]. We have explored the effect of the strength of the anchorings of the substrates on the resulting patterns. We used polymer aligning layers of tunable azimuthal and zenithal strengths to design liquid crystal cells with surface anchorings ranging from ultraweak to strong. We then have studied the patterns formed by the NTB phase of 1,7-bis-4-(4-cyanobiphenyl) heptane (CB7CB). We will show how the period of the stripes can be varied in a large range in cells of the same thickness but with different anchoring preparations. With adequate anchoring conditions (see Fig.1-b-c), an excellent and spontaneous planar alignment of the NTB phase of CB7CB can be obtained much below the phase transition temperature.
References:
[1] Panov V.P. et al, Phys. Rev. Lett., 2010, 105; 167801.
[2] Challa P. K. et al, Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys., 2014, 89, 060501.
[3] Vaupotič N. et al., Chem. Phys. Chem., 2018, 19,2566.
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Dates et versions

hal-02301216 , version 1 (30-09-2019)

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  • HAL Id : hal-02301216 , version 1

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Alaya Soumaya, Abir Aouini, Maurizio Nobili, Ivan Dozov, Daniel Stoenescu, et al.. Role of anchoring on the typical textures of the NTB phase. 19eme Colloque Francophone sur les cristaux liquides (CFCL2019), Sep 2019, Sète, France. ⟨hal-02301216⟩
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