Transition alkyl chain homologs

Table 1. Transition temperatures for the longer alkyl chain homologs of 4-cyano-4 -alkyl- and -4 -alkoxy-biphenyls.

With respect to the unsubstituted polymer, the introduction of a methyl group reduces both the melting and isotropization temperatures by about 80 °C. An increase in the alkyl chain further reduces the transition temperatures, which gradually level off and reach their saturation values corresponding to the polymer homolog with n = 5. 

Fig. 6.1 An example of the experimental phase diagram for a homological series of cinnamate derivatives. The scale of the abscissa means a number of alkyl chains in the tail of a particular molecule. The lines show the location of phase transition temperatures...

Fig. 5.2.4. Phase diagram for theoretical model parameter a. Inset typical phase diagram for homologous series of compounds showing transition temperatures versus length of the alkyl end-chains. (After McMillan. )...

The thermodynamic parameters change almost linearly with the total number of carbon atoms in hydrocarbon chains. The enthalpy increments for transitions are comparable with those for homologous series of n-alkanes, sodium alkyl sulfates, and long-chain alkyltrimethylammonium bromides [22,29-32,66,67], while the entropy change of melting falls within the range of those for stable bilayers of all double-chain amphiphiles, including natural lipids [19],... 

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