Methylene chain length, influence

Considerations by V. Shibaev and N. Plate (see this issue) led to a similar conclusion. Investigations on comb like polymers26), where each monomer unit of the macromolecule carried a non-branched alkyl chain of m methylene groups, have shown that for m > 8 side chain crystallization takes place independently to the main chain conformation. Consequently, if mesogenic molecules are linked to the side chains, they should occupy a l.c. order without influence of the backbone conformation. Following these considerations, alkyl chain lengths m > 8 are necessary for the formation of the l.c. order. As shown later, however, nearly only smectic polymers are possible under these conditions (see Chap. 2.3.3.). 

The increment in ECL value of a given ester over that of the saturated ester of the same chain-length, sometimes known as the fractional chain-length (or FCL) value, is dependent on the stmcture of the compound, and it is influenced by the number of double bonds in the aliphatic chain and the distance of the double bonds from the carboxyl and terminal ends of the molecule. From studies with synthetic fatty acids, such as the complete series of monoenoic (2-18 1 to 17-18 1) [85,323], methylene-interrupted dienoic (2,5-18 2 to 14,17-18 2) [158] isomers and many others [326,387], a picture began to emerge and was well documented by Jamieson... 

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