Core units alicyclic

Here, we report on the use of trisamides as electret additives in i-PP. A general structure of these compounds is shown in Fig. 15. The molecules have a C3-symmetry and consist of a central core, three units capable of forming hydrogen bonds, and nonpolar peripheral substituents. The central core can be a triphenyl-amine, benzene, or cyclohexyl unit. The hydrogen bonds are in most cases formed via amide groups and the peripheral substituents consist of alicyclic or aliphatic linear or branched hydrocarbons. The direction of the linkage between the core and the one, two, or all three substituents can be inverted so that either the carbonyl or the amine groups are attached to the core. 

Similar studies using other ring systems in the central core show that, by and large, the use of nonpolar cores results in the formation of smectic B phases or crystal B phases. Polar cores on the other hand enhance the formation of more disordered smectic phases such as the smectic A and smectic C modifications. Figure 18 shows comparisons for a variety of biphenyl clones [19,25] (where possible for the hexyl and hexyloxy substituted derivatives). In this study, one of the phenyl units has been replaced with an alicyclic or a heterocyclic ring. Resulting cores that are relatively nonpolar tend to exhibit orthogonal ordered phases such as smectic B and crystal B and E phases. For symmetrical polar units (e.g., pyrimidine, tetrazine etc.) smectic A phases tend to predominate, and where one side of the core is more polar (e.g., pyridazine)... 

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