Moieties SCLCP

SCLCPs combine liquid crystalline properties and polymeric behavior in one material. If the mesogenic unit is fixed directly to the polymer main chain, the motion of the liquid crystalline side chain is coupled with the motion of the polymer backbone, preventing the formation of a LC mesophase. Therefore, Finkelmann and Ringsdorf proposed that the introduction of a flexible spacer between the main chain and the mesogenic unit would decouple their motions, allowing the mesogenic moiety to build up an orientational order [29,30]. 

In this chapter we want to discuss the correlation of the mesophase behavior of a cyanobiphenyl-based SCLCP with its backbone structure. As shown before, the backbone structure, the spacer lengths, and the mesogen density per repeat unit have great influence on the LC mesophase evolved. Ligure 8 shows some examples of backbone structures bearing the cyanobiphenyl-moiety that have been reported in literature. The above-mentioned ROMP-derived polymers poly-(II-n) [39],poly-(IV-n) [42,47],poly-(VI-n) [41],andpoly-(VII-n) [53] will be compared with each other and with acrylate-based [56-59], siloxane-based [60] and vinylcyclopropane-based systems [61]. The detected mesophases and their transition temperatures are summarized in Table 6. 

All the examples cited so far involve the formation of side chains by ionic com-plexation. Sallenave and Bazuin studied the selectivity of hydrogen-bond complex-ation in the presence of both ionic moieties and highly polar groups and also investigated the effect of these potentially interacting functions on the thermotropic behavior of SCLCP complexes [28]. A scheme of the compounds studied by these authors is 45 ... 

SCLCPs wherein the NLO active moieties possess mesogenic properties themselves. 

SCLCPs Wherein the NLO Active Moieties Possess Mesogenic Properties Themselves... 

Side chain liquid crystal polymers (SCLCPs) consist of mesogenic structural moieties appended from a polymer backbone (Figure 5.2). The mesogenic units that have been used parallel those previously used for low molar mass liquid crystals, and the stmctural nature of the polymer backbone is widely variable. The mesogenic units (usually calamitic but many discotic types exist) are invariably separated from the polymer backbone by fairly long spacer units which are usually several methylene (-CH -) units,... 

In the smectic phase of scLCPs, interactions between the liquid-crystalline and the backbone chain moieties takes a much more dramatic form. The side chains form the strongly interacting part of the smectic layers, while the weakly interacting backbone chain completes the layer and is basically excluded from the strongly interacting part. In a well-developed smectic phase the main chain thus finds itself very nearly confined to a two-dimensional plane within the smectic layers, with occasional interlayer hopping (see Fig. 4.13(c)). 

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