Nematic liquid crystals polymerization

The order and mobility of a labeled flexible alkyl spacer in the linear thermotropic polymeric nematic liquid crystal poly(2,2 -dimethyl-4,4 -dioxyazoxybenzenedodecanedioyl-dj0) (poly[oxy(3-methyl-1,4-phenylene)azoxy 2-methyl-1,4-phenylene)oxy(1,12-dioxo-1,12-dodecanediyl-d2oll) is explored with deuterium NMR. The quadrupol splittings of the spacer methylene segments in the nematic melt of the polymer are reported as a function of the temperature and are contrasted with observations on model compounds solubilized in a nematic solvent. 

Pitches can be transformed to a mesophase state by further chemical and physical operations. Heat treatment of conventional pitches results in additional aromatic polymerization and the distillation of low molecular weight components. This results in an increase in size and concentration of large planar aromatic molecular species whereupon the precursor pitch is transformed to a mesophase state exhibiting the characteristics of nematic liquid crystals (1). Additional heat treatment converts the mesophase pitch to an infusible aromatic hydrocarbon polymer designated as coke. 

In this brief review, we strive to construct a coherent picture of our current theoretical understanding of the flow and rheology of small-molecule and polymeric nematic liquid crystals. Owing to space limitations, we have presented results selectively, based more on the need to tell a somewhat coherent story than the significance of the work. 

Chiral disubstituted PEDOTs have recently been prepared for the first time via transetherification of 3,4-dimethoxythiophene monomers with chiral glycols followed by potentiodynamic oxidation.174 An alternative approach to optically active PEDOTs has also been recently described, which involves the electrochemical polymerization of the EDOT monomer in aqueous hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal to give a chiral PEDOT/HPC hybrid.175 The PEDOT prepared in this chiral nematic liquid crystal exhibited optically active electrochromism in that it could be electrochemically switched between a dark blue reduced state and a sky blue oxidized form that exhibited a different CD spectrum. 

On the other hand, orientation is one of the most important factors to enhance the conductivity of one dimensional pi-conjugated polymers like polyacetylene. Several attempts were made to obtain an oriented polyacetylene [3-5]. Akagi and Shirakawa applied magnetic force into a polymerization system consisting of nematic liquid crystals and obtained a highly oriented polyacetylene. Kahlert and Leising synthesized an oriented polyacetylene film by pyrolyzing prepolymers. Ozaki polymerized acetylene on the surface of benzene crystals and prepared an oriented polyacetylene. 

Equation 19 introduced above is useful for discussing a process of structural re-formation of a nematic polymeric liquid crystals. The analysis in terms of Eq 19 makes it possible to evaluate the orientational relaxation time t in a force-free state of a nematic liquid crystal despite actual existence of wall and disclination effects. Figure 9 gives an example of computer-fitting for the experimental result shown in Fig. 4 (t = 6.9 sec 1) ... 

Figure 6.2 Examples of static self-assembly, (a) Crystal structure of a ribosome, (b) Self-assembled peptide-amphiphile nanofibers, (c) An array of millimeter-sized polymeric plates assembled at a water/perfluorodecalin interface by capillary interactions, (d) Thin film of a nematic liquid crystal on an isotropic substrate, (e) Micrometer-sized metallic polyhedral folded from planar substrates, (f) A 3-D aggregate of micrometer plates assembled by capillary forces.

Chiral Dopants and Chiral Nematic Liquid Crystals Acetylene Polymerization in Chiral Nematic Liquid Crystal Characterization of Helical Polyacetylene Film... 

Acetylene Polymerization in Chiral Nematic Liquid Crystal... 

Figure 3. The SEM picture shows the bead-like morphology of RM1 polymerized in a nematic liquid crystal (KIS).

Polymerization of Acetylene by Using Nematic Liquid Crystals (NLC)... 

The first work on acetylene polymerization in a liquid crystal medium was done in the mid-1980s [50-56]. The liquid crystal polymerization method was used for the preparation of highly aligned PA films directly through the anisotropic reaction field produced by macroscopically oriented nematic liquid crystals used as a polymerization solvent for the Ziegler-Natta catalyst. 

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