Hybrid liquid crystalline

Abstract We review thin-film morphologies of hybrid liquid-crystalline/amorphous block copolymers. The microphase separation of the blocks and the smectic hquid crystalline ordering within one of the blocks are treated systematically in terms of the interaction parameters. The competition of the tandem interactions in terms of length scales and of surface anchoring can be used advantageously to control the orientation of block interfaces for nanopatterning. 

LAUS ET AL. Hybrid Liquid-Crystalline Block Copolymers... 

Hybrid Liquid Crystalline Polymers and Elastomers for Soft Actuation... 

The combination of crown ethers with mesogenic groups is interesting because the resulting hybrid materials possess the properties of both constructive subunits, i.e., liquid crystalline order in the mesophase and the ability to complex specific cations selectively according to the crown ether cavity size. 

In summary, metallomesogens of crown ethers are interesting compounds that combine a variety of properties (1) appropriate metal centers can show luminescence, (2) all properties can be tuned by the addition of alkaline metal salts to the crown ether, and (3) ordered, liquid crystalline phases are possible. With these hybrid materials, interesting applications can be foreseen in the near future. 

A more recent trend in polymer materials research is the hybridization of cellulosic polysaccharides with inorganic compounds natural and synthetic layered clays, silica, zeolites, metal oxides, and apatites are employable as nanoscale components. In addition, if mesoscopic assemblies such as liquid-crystalline ordering are used in the construction of new compositional systems, the variety of functionalized cellulosic materials will be further expanded. 

Physically, the membrane may exist in two states the "solid" gel crystalline and the "liquid" fluid crystalline states. For each type of membrane, there is a specific temperature at which one changes into the other. This is the transition temperature (Tc). The Tc is relatively high for membranes containing saturated fatty acids and low for those with unsaturated fatty acids. Thus, bilayers of phosphatidylcholine with two palmitate residues have a Tc = 41°C but that with two oleic acid residues has a Tc = -20°C. The hybrid has a Tc = -5°C. Sphingomyelin bilayer, on the other hand, may have a Tc of close to body temperature. In the gel crystalline state, the hydrophobic tails of phospholipids are ordered, whereas in the fluid crystalline state they are disordered. At body temperature, all eukaryotic membranes appear to be in the liquid crystalline state, and this is caused, in part, by the presence of unsaturated fatty acids and in part by cholesterol. The latter maintains the fatty acid side chains in the disordered state, even below the normal Tc. There is thus no evidence that membranes regulate cellular metabolic activity by changing their physical status from the gel to the fluid state,... 

Although a number of salts having organic chains have been synthesized to date, only a few salts were obtained as liquid or glass. In the case of the polyether/salt hybrid, the crystalline phase of both the salt and polyether disappear under appropriate conditions (Figure 22.2). The Polyether moiety in the polyether/salt hybrid is assumed to inhibit the crystallization of the salts by its flexible segmental motion. Since polyethers help dissociate the bound salt through their ion-dipole interactions, the polyether/salt hybrid inherently shows ionic conductivity. 

In addition to the symmetry both linearity and planarity of the AT-phenyl-phthalimide group are important aspects. Tertiary amines are well known to possess a pyramidal structure due to the partial sp 3-hybridization of the nitrogen. Such a pyramidal structure has also been calculated for AT-phenylphthalim-ide by the Tripos-Forcefield programm (Fig. l,top) [19]. However, the more sophisticated PCFF-91 forcefield programm of Biosym yielded a linear structure and a torsion angle of 17° for the AT-phenyl bond (Fig. 1,bottom) [20]. Only the assumption of a linear structure agrees with the experimental observations that 1,4 disubstituted AT-phenylphthalimides may be liquid crystalline. 

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