State mesomorphic

These differences on the stress-strain behavior of P7MB and PDTMB show the marked influence of the mesomorphic state on the mechanical properties of a polymer. When increasing the drawing temperatures and simultaneously decreasing the strain rate, PDTMB exhibits a behavior nearly elastomeric with relatively low modulus and high draw ratios. On the contrary, P7MB displays the mechanical behavior typical of a semicrystalline polymer. 

Note 3 A compound which can exist in a mesomorphic state is usually called a... 

Note 4 A vitrified substance in the mesomorphic state is called a mesomorphic glass and is obtained, for example, by rapid quenching or by crosslinking. 

Mesomorphic state having long-range orientational order and either partial positional order or complete positional disorder. 

The macromolecular nature provides an interesting feature of LC polymeric cholesterics, namely the possibility of obtaining monochromic films. Thus for polymeric liquid crystals the helix pitch is practically not altered with temperature below Tg, when a cholesteric phase is frozen in a glassy matrix (Fig. 23a). This implies that fast cooling of polymeric films from a mesomorphic state (shown with arrows) fixes their optical properties, which makes it possible to use them at ordinary temperatures as selective monochromic reflectors. On the other hand, such polymeric films display the extraordinary polarizing properties of cholesterics, i.e. the different absorption... 

The contemporary period is characterized by a rapid accumulation of information about thermotropic polymeric liquid crystals. It is yet too diversified and, as a rule, gives only a qualitative description of the observed phenomena. The next step in LC polymer investigations should be aimed at a quantitative description of their behaviour. This approach should necessarily lead to progress in the comprehension of the quite peculiar mesomorphic state of matter as well as in the introduction of LC polymers into technological practice. 

The state of the hydrocarbon chains in mesophases and micelles is reflected in the Krafft phenomena. In aqueous solutions of surfactants the Krafft point is defined as the temperature at which the solubility reaches the critical micelle concentration when the temperature is increased further, the solubility rises rapidly since the monomers form micelles (Figure 5) (10). Lipids that do not form micelles frequently start to swell by the uptake of water at a well-defined temperature they are transformed into a mesomorphous state (Figure 6) (11) The relation between these two Krafft phenomena is explained to some extent by the... 

Finally, 13C-NMR with cross-polarization and magic angle spinning (13C-CP/MAS) has been used to examine changes in the mesomorphic states of phospholipids at various temperatures in the absence and presence of the two drugs. Three effects were followed ... 

Chien and Cada [42] have prepared optically active and photoactive SCLC copolymers, 15, with the 4-alkoxyphenyl-4 -alkoxycinnamate chromophore, with the intention of creating LC polysiloxane networks that could be used to prepare macroscopically oriented organic ferroelectric polymers for electro-optical devices. Optical activity was introduced into the polymer by the use of a chiral spacer. Those copolymers which were mesogenic exhibited properties characteristic of a Sc. phase. UV-irradiation of thin films of the polymers in their mesomorphic states at 90°C, led to a loss of the IR absorption at 1635 cm-1 that is due to the cinnamate double bond, and to cross-linking. Long-term irradiation led to... 

Studied in ref. [26] is the effect of HFC reaction conditions on the configuration sequences in POCS-4. Since the mesomorphous state in PMCS-4 is formed in stereoregular trans-tactic polymers only [27, 32] and spatial configuration of initial monomers is not always fully preserved in poly-mers, the effect of HFC conditions on transformation of =Si-CI and =Si-OH centers in initial corn-pounds has been studied. The detected fact of cyclosiloxanes partial inversion at Cl atoms substitution at silicon was expected, as reported before [33, 34], More detailed description of reflex correlation was carried out in ref. [35], Symbols and mark projections of units and bonds to the pla-ne perpendicular to the cycle plane. 

To obtain fuller picture on the cyclolinear polyorganosiloxanes tacticity effect on formation of crys-talline and mesomorphous states, by N.N. Makarova and her co-workers the PMPCS-4 and PPCS-4 were synthesized and their properties were studied. 

Hence, it was concluded [27, 36, 50] that independently of dominance of one of the sequence types (tt, cc or ct) or they all exist simultaneously (atactic polymer), all POCS-6 polymers may exist in the mesomorphous state in a wide temperature range. 

ECTSS-1 and ECTSS-2, they are in the mesomorphous state below the isotropization temperature, Tiso, transiting into mesomorphous glass below glass transition temperature, 7g. 

PDES) is a thermotropic liquid-crystal material. It exists in the mesomorphic state for a certain temperature range after melting of the crystalline phase (i5). This property is due primarily to the side chains. This material has two crystalline forms, a and P, and these crystalline forms go through isomorphic transitions from al to a2 and from pi to P2 when the temperature increases. These transitions occur because of ethyl group reorientation (i6), which has an activation energy of 9.3 kcal/mol. The previous experimental results (16) did not identify the initial and final orientations. In this study, we identified these orientations by using conformational analysis. 

Liquid-crystalline phases are characterized to some degree by the shape of the molecules and by their packing arrangements and ordering in the mesomorphic state. Typically, molecules can have cither disc- or rod-like shapes and can form discotic or calamitic mesophases, respectively. Ferrocene liquid crystal systems that have so far been synthesized tend to have molecular structures that are lath- or rod-like in shape, and consequently the phases observed are calamitic. However, this does not preclude the possibility that a polysubstituted ferrocene could be prepared where the molecular shape is disc-like, thereby holding out the prospect of possibly producing discotic/columnar phases. 

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