Low molecular weight mesogen

As briefly mentioned earlier, thermal studies have been used in conjunction with characterization by polarized light microscopy to determine the miscibility of polymeric and small molecule liquid crystals and low molecular weight mesogens, of the same or different types of liquid crystallinity, can also be used as plasticizers or diluents for polymers, as demonstrated in a study involving side chain liquid crystalline polymers... 

Thermotropic side-chain ionic liquid-crystalline polymers are particularly attractive when the aim is that of merging the liquid-crystalline characteristics of the low molecular weight mesogen side groups with the mechanical properties of the polymeric main chain. It is not surprising, then, that they attracted most of the research efforts in the polymeric ionic liquid crystals field. 

W. Wedler, D. Demus, H. Zaschke, K Mohr, W. Schafer, W. Weissflog, Vitrification in low-molecular-weight mesogenic compormds. J. Mater. Chem. 1, 347-356 (1991)... 

The mesomorphic state may be realized in two ways, namely, the two ways in which ordinary fluid phases are formed from solids dissolution and fusion. These two categories of mesomorphism are called lyotropism (liquid-crystalline solutions) and thermotropism (liquid-crystalline melts), respectively. The latter category consists of single-component substances and encompasses the large variety of low molecular weight mesogens used in LCDs. More recently, thermotropic specialty polymers... 

The difference between the hydrogenated and fluorinated compounds lies in the fact that the former give only N and SmC phases (see Sec. 4.1.4. of this chapter) while the latter display SmA and SmC phases with a perfluorinated (31a) chain and SmC or SmC phases for a semi-perfluorinated chain (31b). First discovered in 1982 with polar rod-like molecules [39], the ribbon SmC phase was then found in low molecular weight mesogens devoid of a CN or NO2 group. With their perfluorinated stiff rod, the compounds 31a are similar to polar... 

For crystallizable rigid-chain polymers, a transition not directly into the isotropic state, but into an intermediate liquid-crystalline state should be observed above their melting point, as this takes place for low-molecular-weight mesogenic compounds. The different variants of the transitions in crystallizable (C), noncrystallizable (NC), flexible-chain (FC), and rigid-chain (RC) polymers in the crystalline (Cr), liquid-crystalline (LC), and amorphous (Am) states are schematically illustrated in Fig. 2.1 [1]. 

The optically active low molecular weight mesogens employed were either 4 -(2-methylhexyloxy)-biphenyl-4-carboxylic acid (6) or terephthal-ylidene-bis[4-(4 -methyIhexyloxy) janiline] (7). 

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