Polymers discotic

Fig. 14 An achiral discotic polymer and the chiral dopant used to induce chiral columnar packing, as represented schematically in the lower part [120]...

Lyotropic SCLCP are far less well studied by rheology than lyotropic MCLCPs. An example is the discotic SCLCP, as mentioned in Chap. 6 (Fig. 6.15), by Franse et al. (2002-2004). Fig. 16.37 gives a schematic representation of side chain discotic polymers (Franse, 2002). In solution the polymers have a tendency to form networks due to interaction between the discotic side chains. From viscoelastic measurements (G and G" as functions of angular frequency) it appeared that the networks formed in a 13% solution in 1,1,2-trichloroethane are very fragile, with a rubber modulus of not more than IN/m2. 

Fig. 17 Discotic polymer architectures. A MCLCP B SCLCP C discotic network...

Corhin PS, Zimmermann SC (2005) Hydrogen bonded supramolecular polymers linear and network polymers and self-assembhng discotic polymers. CRC press, Boca Raton, El, p 153... 

Fig. 1.1.10. Mesophases of discotic polymers (a) the hexagonal columnar phase. The diagram illustrates intercolumnar binding as well as intracolumnar back-folding of the main chain (Herrmann-Schonherr, Wendorff and Ringsdorf ) (b) the sanidic nematic phase composed of boards stacked parallel to one another (Herrmann-Schonherr et a/. ) (c) the columnar nematic phase (Ringsdorf...

Similar results have been obtained by, M. Ebert, O. Herrmann-Schonherr, and J. H. Wendorff, Makromol. Chem. Rapid Comniun., 9, 445 (1988), in their X-ray study of the phase of a sanidic discotic polymer. Evidence of biaxiality in certain nematic polymers has also been reported by Hessel and Finkelmann and by Windle et al. ... 

The formation of polymers of this intermediate compounds in the synthetic pathway to discotic polymers have been examined, their phase behaviour is discussed. 

The basic requirement for a controlled synthesis of discotic polymers is the possibility of introducing different substituents in the trisubstituted central core. 

The diol-compound representsnot only one of the key-compounds along the controlled way to related discotic polymers, but is already a liquid crystalline compound itself. 

The controlled synthesis of discotic polymers requires a functionalized tristar-discogen-monomer. The described reaction of 3,4,5-tris(alkoxy)benzoic acid chloride with protected cis,cis-phloroglucit and the subsequent deprotection leads to a first key-compound in this synthetic pathway the diol-compound 4, member of a novel class of discotic associates. A controlled functionalization of the 3,4,5-tris(alkoxy)derivatives should lead to the second key-compound in the stepwise synthesis of discotic polymers. 

We end this chapter with a very brief account of a new class of liquid crystal polymers, i.e. discotic polymers [118-126]. The basic monomer units are discotic mesogen-ic moieties, which are components of the polymer main chain itself or are attached to the polymer backbone as side groups. A few examples are shown as structures 14-16. Besides the columnar phase, some new types of mesophase have been identified. A... 

Figure 34. Orientations of the molecules in stretched samples of discotic polymers (a) main chain discotic polymer (b) side group discotic polymer. (From Huser et al., [126], reproduced by permission of the American Chemical Society).

Figure 33. Mesophases of discotic polymers (a) hexagonal columnar phase (b) the board-like, or sanidic, nematic phase (c) the columnar nematic phase.

Class C, discotic polymers. Here a variety of molecules have already been synthesized, including polysiloxanes, polyamides and polyesters. These materials exhibit low molecular mobility. Two subclasses were distinguished in the original classification, but now we need to recognize three ... 

Fig. 4.22. Schematic representation of a discotic polymer liquid crystal investigated by Vallerien et al Arrows indicate rotations of the ester groups responsible for dielectric relaxation spectrum of this material. (From Ref. 106, with permission of Steinkopff Verlag.)...

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