Polymers, peculiar features group

Apparently, coexistence of at least two (and probably even more) types of packing constitutes one of the peculiarities of LC polymers with mesogenic side groups. This feature, probably, is exclusive to polymers, as no similar phenomena have been observed in low-molecular liquid crystals. 

It is worth noting that all these latter examples of materials whose key feature calls upon a specific behaviour of furan moieties, require modest contributions from these heterocycles in terms of its quantitative presence in the macromolecules. This situation is similar to that described in Section 6.5.2, in which furan derivatives were used to modify the end groups of some polymers or to synthesize block copolymers by cationic polymerization. In both instances, therefore, it is not the dominant presence of the heterocycle that determines the specific properties of the final materials (as in the case of polymers and copolymers bearing furan monomer units), but instead the fact that a small or even minute percentage of these structures introduces an original mechanistic feature, associated with the peculiar chemistry of the heterocycle, which transforms the behaviour and properties of the final material. This crucial point will be met again in the context of the application of the DA reaction in Section 6.8. 

The introduction of localized defect states by injected charges is not peculiar to polyacetylene. Rather, it is a general feature of certain amorphous semiconductors (35). Indeed, amorphous semiconductors may be divided into two broad classes disorder dominated and defect dominated. Pendant-group polymers... 

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