Magnetic segregation effect in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov,
• Alexander N. Zakhlevnykh and
• Dmitriy V. Makarov

Beilstein J. Nanotechnol. 2019, 10, 1464–1474, doi:10.3762/bjnano.10.145

• study the orientational transitions in a suspension of carbon nanotubes in a nematic liquid crystal induced by an external magnetic field. The case of a finite orientational anchoring of liquid crystal molecules at the surface of doped carbon nanotubes is considered. It is shown that in a magnetic field

• tricritical behavior is related to the redistribution of the carbon nanotubes (segregation effect) inside the layer. Keywords: carbon nanotubes; liquid crystal; magnetic field; orientational transitions; segregation effect; Introduction Composites of liquid crystals (LCs) and nanoparticles are actively

• -order phase transition, and with κ < κ* to the first-order phase transition. In the case of absolutely rigid anchoring of CNTs with the NLC molecules, Equation 19 takes the form Note that (Equation 15) allows us to determine only the fields of the second-order orientational transitions. Let us find the

Optical orientation of nematic liquid crystal droplets via photoisomerization of an azodendrimer dopant

• Sergey A. Shvetsov,
• Alexander V. Emelyanenko,
• Natalia I. Boiko,
• Alexander S. Zolot'ko,
• Yan-Song Zhang,
• Jui-Hsiang Liu and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2018, 9, 870–879, doi:10.3762/bjnano.9.81

• photoinduced orientational transitions caused by the isomerization of dendrimer dopant under light illumination with different wavelengths. Both NLC droplets in the bulk of glycerol and in contact with the solid substrate are considered. To understand the nature of these transitions, the spatial configuration

• substrate Let us consider the orientational transitions of NLC droplets resting on the cell substrate. Before any LED irradiation, the NLC droplets exhibit homeotropic alignment on the substrate coated with an orienting compound and planar alignment on the glycerol interface. This leads to the director

• = 448 nm (or 422 nm, or 466 nm). Note that the photoinduced transitions between the initial, with one boojum, and the structure free from point defects (Figure 3a,b) were first obtained in [30]. Orientational transitions in NLC droplets resting on the substrate can also occur spontaneously in the same

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2807–2817, doi:10.3762/bjnano.8.280

• planar type when the nanotubes are oriented along the matrix director, and the homeotropic type when the nanotubes are perpendicular to the director). The possibility of a redistribution of the nanotube concentration (segregation effect) is shown. The fields of orientational transitions between uniform

• first or of second order depending on the carbon nanotubes segregation intensity. Keywords: carbon nanotubes; liquid crystal; magnetic field; orientational transitions; soft coupling; Introduction In recent years suspensions of anisometric particles in liquid crystals have become of great interest for

• than that of the pure LC even for a low concentration of the dispersed phase (0.01 vol %). The new approach has opened the way for the creation of devices that operate on the basis of magnetic orientational transitions in the LC. To date, many theoretical and experimental studies on the properties of

Ferrocholesteric–ferronematic transitions induced by shear flow and magnetic field

• Dmitriy V. Makarov,
• Alexander A. Novikov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2552–2561, doi:10.3762/bjnano.8.255

• magnetic field depends on the magnetic field orientation, the velocity gradient, and the viscous coefficients. We show that the interplay of a magnetic field and a shear flow can induce reentrant orientational transitions that are ferrocholesteric–ferronematic–ferrocholesteric. Keywords: ferrocholesteric

• the spiral structure of the cholesteric liquid crystal. The diagrams of the cholesteric–nematic orientational transitions induced by a shear flow and a magnetic field were calculated in [20]. The deformation of the spiral orientational structure of a cholesteric liquid crystal under a combined effect

• interval correspond to the same value of hc. This means that for the fixed values of u and h the rotation of the magnetic field can induce a sequence of reentrant ferrocholesteric–ferronematic–ferrocholesteric transitions. The reason for the appearance of reentrant orientational transitions is associated