Interfaces nematic

Today, the orienting action of any interface (nematic/another phase) on the... 

Stelzer et al. [109] have studied the case of a nematic phase in the vicinity of a smooth solid wall. A distance-dependent potential was applied to favour alignment along the surface normal near the interface that is, a homeotropic anchoring force was applied. The liquid crystal was modelled with the GB(3.0, 5.0, 2, 1) potential and the simulations were run at temperatures and densities corresponding to the nematic phase. Away from the walls the molecules behave just as in the bulk. However, as the wall is approached, oscillations appear in the density profile indicating that a layered structure is induced by the interface, as we can see from the snapshot in Fig. 19. These layers are... 

The alignment of the director at the nematic free surface of real systems is not found to exhibit universal behaviour. Depending on the mesogen, homeotro-pic, tilted and planar anchoring have been observed. Clearly, to study this interface in a simulation a potential which exhibits a nematic phase in co-... 

Fig. 23a,b. Snapshots of configurations showing a the nematic-isotropic b the smectic A-isotropic interfaces. The Gihhs dividing surfaces are indicated hy the dashed lines... 

We have little information on the way low molecular weight molecules and oligomers adsorb (19). Apparently below DP s of about 100 they lie flat on the surface for concentrations up to a monolayer of segments, then seem to form thicker islands of smectic or nematic structure. Ordered condensed mono, -di, -or multi-layers are primarily the arrangements of smaller, especially amphipa-tic molecules on liquid-liquid interfaces. Polymers are too large to adsorb, in the ordinary sense, on micelles but segments of linear polymers may act as nucleation centers for micelles of small molecules which probably is one of the mechanisms for the lipid-, or detergent-, polymer interaction. 

The dry nematic solution exhibits a smooth texture after being annealed, with a field of disclinations at any glass-solution interface. A nematic phase produced by cooling the isotropic phase will exhibit a complex, mottled texture that slowly anneals to the smooth texture. The ratio Rvv(q)/ Hv(q) (for e = 20 deg.) for either morphology indicates appreciable orientational averaging of the orientation fluctuation. Photon correlation scattering on the... 

Spherical droplet that forms during a transition from an isotropic phase to a nematic mesophase. It has characteristic textures that depend on the droplet size and the director orientation at the nematic-isotropic interface. 

Note 3 A bipolar droplet texture occurs when the director lies in the plane of a nematic-isotropic interface. 

Note 1 The point defect usually forms when the director is normal to the nematic-isotropic interface. 

Moreover, segregation of nanoparticles at liquid crystal/substrate interfaces is also an effective way to promote or alter the alignment of thin nematic liquid crystal films. Depending on their concentration, size, and nature, several types of nanoparticles have been shown to induce homeotropic alignment as well as defects and remarkable defect patterns. 

Tuning of the pre-tilt angle at the interface was also demonstrated by doping commonly used polyimide alignment layers with POSS nanoparticles [339]. In addition, the fabrication of a tunable liquid crystal flat microlens was achieved by placing a drop of a nematic liquid crystal doped with POSS nanoparticles onto a substrate inducing planar alignment (local HAN mode) [340]. Simultaneously, Takatoh and co-workers extended this concept to a series of metal oxide... 

Yokoyama, H., and Van Sprang, H. A. A novel method for determining the anchoring energy function at a nematic liquid crystal-wall interface from director distortions at high fields./. Appl. Phys. 57, 4520 (1985). 

R. L. C. Vink, and T. Schilling (2005) Interfacial tension of the isotropic-nematic interface in suspensions of soft spherocylinders. Phys. Rev. E 71, 051716... 

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