Linking SCLCP

All Liquid Crystal Polymers are characterised by the fact that they contain stiff meso-genic groups, often inserted in flexible chain systems (so called "spacers") and connected to them by linking functional groups the mesogenic unit is inserted either in the main chain or in the side chains or (in exceptional cases) in both. We shall discuss MCLCPs and SCLCPs. A schematic representation of common structures of LCPs is displayed in Fig. 6.14 (Jansen, 1996). An example of a SCLCP with disc-like mesogens is displayed in Fig. 6.15 (Franse et al., 2002, 2004). 

Zhang and coworkers chose a base polymer alternative to poly(styrenesulfonate) and prepared SCLCP with a polysiloxane backbone [102]. Differently from the previous cases, side groups were linked to the main chain by covalent bonding. 

The reasons for employing a flexible spacer that links the mesogenic nnit to the polymer backbone are discussed above. The influence of the flexible spacer that is normally essential for the generation of mesophases in SCLCP is of great interest Figure 5.5 shows some examples of simple flexible spacers where the actual size of the spacer may be smaller or larger. 

From the point of view of molecular architecture, as schematically shown in Figure 9.3, two types of LCP have been developed (1) main-chain LCPs (MCLCPs), having the monomeric liquid crystals (i.e., mesogenic group) in the main chain of flexible links, and (2) side-chain LCPs (SCLCPs), having the monomeric liquid crystals attached, as a pendent side chain, to the main chain. 

For example, the interplay between the backbone chain and the mesogenic side chains can make the nematic phase of scLCPs more complex than a normal nematic (cf. Section 4.3). The nature and magnitude of such an interlay may be expected to depend, to a large extent, on the length, stiffness and shape anisotropy of the otherwise weakly interacting spacer group linking the side chains to the main chain. In the... 

As discussed in Chapter 1 by Brostow, side chain liquid crystal polymers can be realized in many distinctive architectures. Dielectric relaxation studies were, however, performed mostly on a type of scLCP in which mesogenic groups are linked at one end to a backbone-chain via a... 

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