Phases smectic liquid crystals

However in chiral tilted liquid crystal smectic phases, the polarization is driven by the tilt angle, and the phase transition will not necessarily be of second order. 

The systematic synthesis of non amphiphilic l.c.-side chain polymers and detailed physico-chemical investigations are discussed. The phase behavior and structure ofnematic, cholesteric and smectic polymers are described. Their optical properties and the state of order of cholesteric and nematic polymers are analysed in comparison to conventional low molar mass liquid crystals. The phase transition into the glassy state and optical characterization of the anisotropic glasses having liquid crystalline structures are examined. 

The final group of lamellar phases to be introduced here are the so-called crystal smectic phases. These are more ordered than the previous smectic examples and are characterized by the appearance of interlayer correlations and, in some instances, by the removal of freedom of molecular rotation. Consequently the (crystal) B, G and J phases are derived from the Sb, Sf and S] phases, respectively, but with the presence of interlayer correlations. Further the (crystal) E, H and K phases are B, G and J phases which have lost rotational freedom. These phases are still disordered and hence, still intermediate between the solid and liquid states. 

While all of the previously described phases are genuine liquid-crystalline phases, there are other phases in which there is long-range positional order. They differ from true crystal phases in one important aspect the molecules in them have the freedom of (at least) rotation around their long axis their thermal motion is not completely frozen out. These phases are labelled crystal smectic phases (denoted by the letters B, E, G, H, J, K). 

The photodimerization of the anthracene (176) having a 9-dendritic substituent has been studied within the vaterite crystal of CaCOs (R = H),"" and in its liquid crystalline smectic phase (R = Me). The crystal phase of the CaCOs is... 

The true liquid-crystal mesophases of calamitic mesogens are divided into two classes—the nematic and smectic phases and these will be described in turn. There is, in addition, a series of crystal smectic phases that are not really liquid-crystal phases but which for many years were classified as such these will be mentioned briefly below. 

The molecular organization in thermotropic liquid-crystal line phases is associated predominantly with a rigid anisometric architecture of the constituent single molecules. The triazines 13 were the first examples of electron donors that fotm columnar phases, which give rise to the induction of smectic liquid crystalline structures through donor-acceptor interactions (Figure 11). 

Initially smectic phases can be subdivided into the true liquid crystal smectics and the... 

The FLCs or AFLCs mentioned above are liquid crystalline materials showing a chiral smectic C phase or related phases. Although nematic liquid crystal possesses only directional order, smectic liquid crystals shows layer structures or periodic order of the liquid crystalline molecular centres. In this respect, smectic liquid crystalline materials have more in common with crystalline materials than with nematic liquid crystalline materials. As a result, the alignment of smectic liquid crystal is quite different from that of nematic liquid crystals. Smectic liquid crystals show a large variety of defects because they possesses highly ordered structiu-es. Moreover, the layer structures are irreversibly destroyed by applying stress. This phenomenon poses a major problem for display applications. Therefore, several techniques to prevent the application of force to the liquid crystalline materials of FLC or AFLC devices have been proposed. 

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