Liquid Crystalline LC Polymers

For such materials, which may be smectic or nematic liquid crystals, the dielectric properties of the LC phase are anisotropic. Fora uniaxial LC phase, the dielectric tensor is diagonal such that 

DRS provides a particularly usdul means of monitoring the nature and extent of macroscopic alignment in SCLC samples that have been subjected to E fields, B fields, surface forces or are aligning/disaligning after electrical and/or thermal treatments. As we have shown [5Q, the complex permittivity of a uniaxial sample of intermediate alignment is given, to a good approximation, by the linear-addition relationship 

The field-free orientation distribution function /°(Dq) field-perturbed 

When the dipolar units reorientate in the LC potential, the conditional probability of finding the dipole group in the orientation around Q at time t given that it was around the orientation at t = 0 is given formally by the further expansion 

The dipole moment in the laboratory frame (X, Y,Z) following the step withdrawal of the measuring electric field is then determined from the relationship [57] 

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The mesophases formed by liquid crystalline (LC) polymers are well known to impart strength, toughness, and thermal stability to plastics and fibers (1-5). While LC polymers have been widely studied, their potential utility as coatings binders seems to have been overlooked. Among the very few reports that may describe LC polymers in coatings are patents claiming that -hydroxybenzoic acid (PHBA), a monomer commonly used in LC polymers, enhances the properties of polyester powder coatings (6-9). 

The article covers synthesis, structure and properties of thermotropic liquid-crystalline (LC) polymers with mesogenic side groups. Approaches towards the synthesis of such systems and the conditions for their realization in the LC state are presented, as well as the data revealing the relationship between the molecular structure of an LC polymer and the type of mesophase formed. Specific features of thermotropic LC polymers and copolymers of nematic, smectic and cholesteric types are considered. 

Wan et al. used TEMPO-mediated polymerizations to prepare liquid crystalline (LC) polymers [147,148]. pSt-TEMPO was chain extended with a mesogen-jacketed LC monomer, 2,5-bis [(4-methoxyphenyl)oxycarbonyl] styrene (MPCS, Fig. 9) to form a rod-coil diblock copolymer. The resulting copolymer had an Mn=19,500 with an Mw/Mn=1.48. There was tailing to lower molecular weights, indicating the presence of some unreacted macroinitiator, but after extraction with cyclohexane, the remaining macroinitiator was removed, leaving pure block copolymer. H and 13C HMR analysis indicated the presence of both blocks, as did DSC analysis, which showed two Tgs,one at 117.2 °C (pMPCS) and... 

Abstract Liquid-crystalline (LC) polymers that exhibit ionic or electronic conduction are described. Anisotropic and efficient transportation of electrons and ions is expected for these materials. The ordered LC nanostructures of LC polymers having ion- or electron-active moieties are important for efficient anisotropic transport. For electron-conductive materials, we focus on side-chain LC polymers. 

For organic materials, electronic and ionic conduction are important topics [1]. Liquid-crystalline (LC) polymers are good candidates for materials that transport ions and electrons because their ordered nanostructures are expected to induce anisotropic and efficient conduction [2-10]. However, limited numbers of examples have been reported for electron- and ion-active LC polymers, compared to crystalline and amorphous polymers [3-10]. 

Liquid crystalline (LC) polymers -- with a thermodynamically stable liquid crystalline phase above the These were... 

Dielectric spectroscopy (DS) provides a means of studying chain dynamics of amorphous, crystalline, and liquid crystalline (LC) polymers (1,3-5,11). As one example Figure 3 shows plots of s" against log / /Hz for the amorphous polymer poly(vinyl acetate) at different temperatures. The a loss peak (Fig. 3a) is due to the large-scale motions of chain dipoles and moves to ultralow frequencies as Tg is approached. VaiT)) obeys the Vogel-Fulcher-Tammann equation... 

Relationship between structure and properties of liquid crystalline (LC) polymers has been studied extensively. 

There is currently considerable interest in the solid state physics of thermotropic liquid crystalline (LC) polymers and much emphasis is placed on studies regarding the solid-solid transitions and the chain dynamics of these systems. Recently, evidence for the occurrence of supercooled mesomorphic structures in the glassy state of polymers quenched from the anisotropic melt has been presented. ... 

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