Director alignment perpendicular

Figure 3.2b shows the results obtained for a NE prepared by photo cross-linking a NP oriented by a magnetic (G, G ) or an electric field Cj ormai)- Contrary to the case of the NE prepared by the two-step cross-linking process, this preparation method also allows one to obtain a NE with a director aligned perpendicular to the plane of the film, and therefore to measure the shear modulus G ormai- Cike for the previous NE, the data have been taken at 1 Hz and normalized at high temperature. It can be seen that the temperature dependence of shows a slight decrease... 

Moleeular alignment of which the director is perpendicular to a substrate surface. 

An interesting similarity of what we discussed here appears if one deals with mixtures of rodlike and disklike micelles. These systems could behave very similarly to a truly biaxial nematic, but show interesting differences to them. Whereas for the usual orthorhombic biaxial nematics both directors are perpendicular to each other by construction, in mixtures there is no need to impose this restriction. Pleiner and Brand [70] investigated how mixtures are influenced by an external field (magnetic field or shear flow) and found that the angle between the two directors exhibits a flow aligning behavior similar to the one studied in [42,43],... 

A typical experimental apparatus for studying photorefractivity in liquid crystals is illustrated in Fig. 2. Two coherent laser beams from an Ar+ laser are crossed in the sample, with a total of 5 mW of p-polarized output at 514 nm. The beams are unfocused and have a 1/e diameter of 2.5 mm. The liquid crystal composite is sandwiched between two ITO coated glass slides that are coated with octadecyl-silyl groups to induce the liquid crystal director to align perpendicular to the face of the glass slides, that is, homeotropic alignment [43], The cell thickness is determined by a Teflon spacer that is 12 to 100 p,m thick. A small electric field... 

The critical wavevector is perpendicular to, or subtends a large angle with the initial director alignment (contrary to normal rolls) thus, the rolls are parallel (longitudinal) or strongly oblique (see Fig. 13). 

Fig. 3. Network soft, can be transformed like rubber band, but retains its shape and couples to director orientation because (a) director is preferably parallel (or perpendicular) to polymer chains (LC-elastomer) (4 9) (b) director aligns (parallel) to chains in oriented phase-separated polymer network structure (low molar mass LC in LC-thermoset) (9,10).

The formation of transient domain patterns aligned perpendicular to the initial director during the relaxation process of the Frederiks transition has been known since the earliest observations by Carr [20] and Guyon et al. [21]. After these observations some other transient domain structures were found in thermotropic and lyotropic liquid crystal with perpendicular [22], parallel [23], oblique [24], and two-dimensional [25] striped patterns relative to the initial orientation of the director in both the electric and magnetic fields. 

Locally oblate lyotropic elastomers with lamellar phase structure (L -phase) can be oriented by uniaxial compression, as outlined above for thermotropic smectic-A elastomers. Fischer et al. synthesized crosslinked polysiloxane elastomers carrying non-ionic amphiphilic side-groups attached with their hydrophobic end to the polymer backbone. They were able to compress elastomer samples between Teflon half-cylinders to about half of their original thickness. The orientation of the phase structure - except for some unoriented domains - was demonstrated by means of H-NMR spectroscopy on the directly deuterated samples as well as by X-ray scattering. The preferred orientation of the director, and hence the amphiphilic side chains, was found to be parallel to the axis of compression with the amphiphilic bilayers aligned perpendicularly [98, 99]. 

The molecules tend to align perpendicular to the magnetic field direction. The directors of the ordered domains become oriented perpendicular to the field it. 

Most of the aromatic nematogenes of type I belong to this class (cf Table 1). The directors, L, of the nematic domains tend to align perpendicular to the electric... 

Figure 5 Experimental 250 GHz EPR spectra from membrane samples of various DMPC.DMPS compositions. The membranes were fully hydrated and mechanically and aligned with the director vector perpendicular to the external magnetic field. All spectra were recorded at 10°C in the gel phase and are reproduced here from Barnes and Ereed ...

The conditions for the first two viscosity coefficient ratios correspond to Eq. (100). A discussion of the stability of the various solutions is presented in the paper of Saupe [59]. Brand and Pleiner [61] as well as Leslie [62] discuss the flow alignment without the restriction that one director is perpendicular to the shear plane. 

The formation of transient domain patterns aligned perpendicular to the initial director during the relaxation process of the magnetically driven Frederiks transition has been known since the earliest observations [85, 86]. The parallel stripes observed are, in... 

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