Mainchain polymers

Schubert, F. Friedrich, K. Hess, M. Kosfeld, R., "Investigations on Phase Diagrams of a Coil-Polymer (PC) and a Semiflexible Thermotropic Mainchain Polymer (PET-co-PHB) in Solution," Mol. Cryst. Liq. Cryst., 155, 477 (1988). 

Linear mainchain polymer with random dipole arrangement... 

The design and synthesis of mainchain polymers with chromophores in the syndioregic (head-to-head) configuration are reviewed, and recent unpublished results are included. Polymers were designed for both electric-field poling and Langmuir-Blodgett-Kuhn (LBK) deposition. 

E. Kim, H. W. Lee, Photo-induced elecMcal switching trough a mainchain polymer, J. Mater. Chem., 16, 1384-1389 (2006). 

Progressing from guest-host systems (chromophores dissolved in a polymer matrix) to sidechain polymer systems (chromophores chemically attached to a polymer backbone), one arrives at another class of materials where the dipole is actually part of the polymer backbone, i.e., mainchain polymer systems. In fact, there are some reports on mainchain chromophoric copolymers in which the chromophores are attached head to tail. Figure 1 summarizes the four types of polarized organic materials. 

Materials such as the linear or low branched polyurethanes and the polyamides fall into the category of polar mainchain polymers, but their relaxational response is somewhat distinctive, principally because of the occurrence of hydrogen bonds between their chains. 

The same general classification scheme used to describe hydrogen-bonded liquid-crystalline polymers may also be used to describe hydrogen-bonded polymers in isotropic solution. However, this area is less well developed, and few examples have been reported. The first examples described are mainchain polymers constructed from ditopic monomers (Fig. 7). 

There have been a number of attempts to make OLEDs based on discotic liquid crystals although performance is disappointing probably because of aggregation. Wendorff and co-workers demonstrated monoesters of triphenylene 7, see Table 6.2, in their Colp phase and mainchain polymers of triphenylene in the Coin phase in electroluminescent devices. High electric fields were required, 10 V cm , and the lifetimes of the devices are probably not very long [40,41]. The bilayer devices made by Bock and co-workers, e.g., ITO/triphenylene 8 (hole transporter)/perylene 9 (electron transporter)/aluminium [43,44] exploit materials that have liquid crystal phases above room temperature [42, 43]. Simple variants on these structures were synthesised, which had green, blue and sometimes almost white light emission [44]. 

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