Liquid crystalline acids

Liquid Crystalline Structures. In certain ceUular organeUes, deoxyribonucleic acid (DNA) occurs in a concentrated form. Striking similarities between the optical properties derived from the underlying supramolecular organization of the concentrated DNA phases and those observed in chiral nematic textures have been described (36). Concentrated aqueous solutions of nucleic acids exhibit a chiral nematic texture in vitro (29,37). 

Liquid crystalline compounds are not very dangerous and only basic precautions should be used in handling them. They are not poisonous or carcinogenic, and do not cause problems when in contact with skin (see also Biphenyls and terphenyls Cinnamic acid Stilbene dyes). 

Figure 17 Differential scanning colorimetric trace of the liquid crystalline copolyester of 8-(3-phenyl hydroxy) octanoic acid and paro-hydroxy benzoic acid.

Membranes are composed of phospholipids and proteins. The fatty acid composition of the phospholipids in a membrane influences how it is affected by the cold. In general, as the temperature of a cell is lowered the lipids in the membrane bilayer undergo a phase transition from a liquid crystalline (fluid) state to a gel (more solid) state. The temperature at which this transition takes place is very narrow for phospholipids composed of a simple mixture of fatty acids, but is quite broad for the phospholipids in cellular membranes. It is usually implied from various methods... 

In order to make polymers behave as liquid crystals it is necessary to introduce some structural rigidity. A typical polymer which has the required rigidity is poly(phenylenetetraphthalamide) (10.7). This material belongs to a class of polymer known as the aramids. Other liquid crystalline polymers are the thermotropic polyesters derived from /7-hydroxybenzoic acid, p, p -biphenol and terephthalic acid (10.8). 

The effect of incorporating p-hydroxybenzoic acid (I) into the structures of various unsaturated polyesters synthesised from polyethylene terephthalate (PET) waste depolymerised by glycolysis at three different diethylene glycol (DEG) ratios with Mn acetate as transesterification catalyst, was studied. Copolyesters of PET modified using various I mole ratios showed excellent mechanical and chemical properties because of their liquid crystalline behaviour. The oligoesters obtained from the twelve modified unsaturated polyesters (MUP) were reacted with I and maleic anhydride, with variation of the I ratio with a view to determining the effect on mechanical... 

However, the hydrogen-bonded mesogens that are of most interest in the context of this article are those elaborated initially by Kato and Frechet in the early 1990s [24-33]. In this approach, a pyridine, which may or may not have liquid crystal properties, was hydrogen bonded with a 4-substituted benzoic acid to form a new species with its own, distinct mesomorphism. For example, complex 9 shows a SmA phase that persists to 238 °C (n = 2, m = 4), while its free component pyridine is nematic to 213 °C the component benzoic acid is also nematic (as the H-bonded dimer) to 147 °C (although note that the notional monomer would not be liquid crystalline). 

A polycondensation reaction of 4,4 -dihydroxybiphenyl, sebacic, and m-carboranedicarboxylic acids was reported to produce a carborane-containing polymer (142) (Fig. 78) that led to the production of a new columnar phase at elevated temperatures.157 This new phase was formed in addition to the crystalline and liquid crystalline smectic phases typically formed from only 4,4 -dihydroxybiphenyl and sebacic acids. 

G.S. Attard, P.N. Bartlett, N.R.B. Coleman, J.M. Elliott, and J.R. Owen, Lyotropic liquid crystalline properties of nonionic surfactant/H20/hexachloroplatinic acid ternary mixtures used for the production of nanostructured platinum. Langmuir 14, 7340-7342 (1998). 

Benzene oxychlorination process, of phenol manufacture, 18 751 Benzeneperoxyseleninic acid, 13 466 Benzene rings, in liquid crystalline materials, 15 103-104 Benzene sulfonation process, of phenol manufacture, 18 751 Benzenesulfonic acid, 3 602 Benzene-toluene fraction, in styrene manufacture, 23 341-342 Benzene-toluene-xylene (BTX), 10 782 ... 

Bondline readout, 7 122 Bond number (Bo), 15 687t Bond orientational order, of liquid crystalline materials, 15 85 Bonds, fullerene, 12 233-234 Bond strength, in thermal bonding, 17 510 Bone, 7 273t. See also Bones citric acid in, 6 632t Bone fractures, 3 725 treatment, 3 725... 

Jackson, Jr, W. J. and Morris, J. C., Poly esters of 4,4 -biphenyl dicarboxylic acid and aliphatic glycols for high-performance plastics, in Liquid Crystalline Polymers, ACS Symposium Series, Vol. 453, American Chemical Society, Washington, DC, 1990, pp. 16-32. 

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