Coatings chiral nematics

Mixtures of a nematic liquid crystal (LC or LC ) with small quantities of gold nanoparticles coated with alkylthiolates (<5 wt%) including an alkylthiolate functionalized with a chiral group have been studied (Figure 8.29) [72]. All mixtures show nematic mesophases with transition temperatures and phase stability very similar to those oftheliquid crystal precursors LC or LC. The introduction ofachiral center into the mixtures (mixtures of Au ) produce chiral nematic mesophases. A similar result is obtained in mixtures of Au and LC doped with the chiral dopant (s)-Naproxen. 

The electrode surfaces of a normal LCD sandwich cell d 8-10 pm) are coated with an alignment layer in order to induce a planar alignment of a host (chiral) nematic mixture containing the dichroic dye of positive dichroism and a chiral dopant. Due to the absence of polarisers a very thin mirror can be incorporated within the cell on top of the rear glass plate electrode in direct contact with the guest-host mixture, see Figure 3.15. 

Two sets of chiral-nematic hybrid are chemically bonded to the same dithienylethene core as for the photoswitchable nematic GLC (30), resulting in a smectic C -cholesteric GLC as depicted in Fig. 6.10. A sample of (31) was placed between two alignment-coated fused silica substrates for heating to 230 °C followed by cooling to 207 °C, where shearing was applied to induce alignment. The... 

Heux et al. were the first to describe the self-organization phenomenon of CNCs in aprotic solvents. Initially, surfactant coating was used for dispersion of CNCs and obtained a chiral nematic structure with pitch value of approximately 4 pm, whereas in the case of aqueous suspensions it is between 20 and 80 pm. In addition, higher concentration (up to 36%) could be achieved due to steric stabilization exerted by surfactant coating [ 114]. A detailed study of the structure of this phase (chiral nematic) has been reported by the same group [115,116]. 

Interference and angle-dependent color effects can also be achieved by layers or particles based on liquid crystal polymers (LCP) Such effects can, for example, be produced by small plate-like substances which consist of an LCP material itself, or by small platelets which are uniformly coated with a cross-linked liquid crystalline polymer in a chiral-nematic arrangement. ... 

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