Temperature-Driven Anchoring Transitions at Liquid Crystal/Water Interfaces
| Autor: | Yoko Ishii, Teresa Lopez-Leon, Guillaume Durey |
|---|---|
| Přispěvatelé: | Gulliver (UMR 7083), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Brown University, Kyoto University [Kyoto] |
| Rok vydání: | 2020 |
| Předmět: |
Phase transition
Materials science Population FOS: Physical sciences Anchoring 02 engineering and technology Reversible process Condensed Matter - Soft Condensed Matter 010402 general chemistry 01 natural sciences Topological defect Physics::Fluid Dynamics Adsorption Liquid crystal Electrochemistry General Materials Science education Spectroscopy chemistry.chemical_classification education.field_of_study Surfaces and Interfaces Polymer 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences Condensed Matter::Soft Condensed Matter chemistry Chemical physics Soft Condensed Matter (cond-mat.soft) 0210 nano-technology [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] |
| Zdroj: | Langmuir Langmuir, American Chemical Society, 2020, 36 (32), pp.9368-9376. ⟨10.1021/acs.langmuir.0c00985⟩ |
| ISSN: | 1520-5827 0743-7463 |
| Popis: | International audience; Controlling the anchoring of liquid crystal molecules at an interface with a water solution influences the entire organization of the underlying liquid crystal phase, which is crucial for many applications. The simplest way to stabilize such interfaces is by fabricating liquid crystal droplets in water; however, a greater sensitivity to interfacial effects can be achieved using liquid crystal shells, that is, spherical films of liquid crystal suspended in water. Anchoring transitions on those systems are traditionally triggered by the adsorption of surfactant molecules onto the interface, which is neither an instantaneous nor a reversible process. In this study, we report the ability to change the anchoring of 4-cyano-4′-pentylbiphenyl (5CB), one of the most widely used liquid crystals, at the interface with dilute water solutions of polyvinyl alcohol (PVA), a polymer commonly used for stabilizing liquid crystal shells, simply by controlling the temperature in the close vicinity of the liquid crystal clearing point. A quasi-static increase in temperature triggers an instantaneous reorientation of the molecules from parallel to perpendicular to the interfaces, owing to the local disordering effect of PVA on 5CB, prior to the phase transition of the bulk 5CB. We study this anchoring transition on both flat suspended films and spherical shells of liquid crystals. Switching anchoring entails a series of structural transformations involving the formation of transient structures in which topological defects are stabilized. The type of defect structure depends on the topology of the film. This method has the ability to influence both interfaces of the film nearly at the same time and can be applied to transform an initially polydisperse group of nematic shells into a monodisperse population of bivalent shells |
| Databáze: | OpenAIRE |
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