Highly ordered smectic phases

X-ray measurements have shown that the positional and orientational ordering in highly ordered crystalline smectic phases is more comparable with the ordering in the solid state than the structures of the fluid smectic phases and the nematic phase. Therefore, a comparison of the structures of crystals and highly ordered smectic phases is possible because of their closer similarities. Up to now, only the crystal structures of few mesogenic compounds exhibiting highly ordered smectic phases have been reported in... 

This assertion is borne out by the small deviations from fluid-isotropiclike values of the photoproduct ratios found in the Norrish II reactions of the two alkyl perfluoroalkyl ketones 76 (with m, n = 7,8 and 9,10) in the (macroscopically) highly ordered smectic phases of F10H10 [273,274]. As... 

Some examples of pyrrolidinium-based ILCs have been reported in recent years, in all cases forming smectic phases, from low ordered SmA phases of de Vries type to highly ordered smectic phases of T type. These will be discussed in the following paragraphs. 

For application to thin film transistors (TFTs), which can operate electronic papers, high carrier mobility exceeding 0.01 cm2 V-1 s-1 is necessary. For this purpose, nematic semiconductors with low molecular order, resulting in relatively low carrier mobility, are not suitable. For application of thin films of semiconductors to TFTs, stabilization of the highly ordered smectic phases, which exhibit high carrier mobility, by photopolymerization may be desirable. Kreouzis et al. studied the carrier transport properties of photopolymer-izable phenylnaphthalene, diphenylbithiophene, and quaterthiophene derivatives having an oxetane moiety or l,4-pentadien-3-yloxy in their alkyl side chain (Fig. 21) [107,108],... 

Fig. 21 LC semiconductor containing an oxetane moiety, which retains highly ordered smectic phase around room temperature...

SmX-SmC transition temperature, SmX high order smectic phase. 

The success in constmcting highly ordered smectic phase in solution by using modified polydisperse polypeptide homopolymers rather than monodisperse... 

Identification of Highly Ordered Smectic Phases in a Series of Main-Chain Liquid-Crystalline Polyethers... 

In summary, TPPs show complicated phase transition behaviors. Their phase diagrms are established and various phases are identified via the thermodynamic transition properties obtained from DSC, the structural order and symmetry determined by WiOCD, and morphology and defects observed under PLM and TEM. In particular, the WAXD fiber patterns in different phases play the most important role in determining the phase structures and symmetry. It is evident that the concepts of highly order smectic phases developed in small-molecule liquid crystals can also be utilized in the main-chain liquid crystalline polymers. 

Larger differences were found for the more highly ordered smectic phases, and for ketones bearing substituents which mimic the structure of the mesogen. From an analysis of the results of a number of studies, it was concluded that the effects observed were the result of the solvent s ability to alter the equilibrium constant for trans/ gauche interconversion in favour of the nonquenching tra 5-conformer. These studies included a careful determination of the solubility limits of each solute in the various phases by deuterium nmr spectroscopy and thus also provide several clear examples of the effects and complexities of biphasic solubilization on solute reactivity. 

Funahashi, M., Zhang, F., Tamaoki, N. High ambipolar mobility in a highly ordered smectic phase of a dialkylphenylterthiophene derivative that can be applied to solution-processed organic field-effect transistors. Adv. Mater. 19(3), 353-358 (2007)... 

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