Supermolecular Liquid Crystals - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 22

Fig. 24 The change in transition temperatures ( ◦ C) as the number of mesogenic groups
increases
dral siloxane-substituted systems, as the central cores of the supermolecular
systems, allows for meaningful comparisons to be made as the free volume
available to the mesogens is reduced as the degree of substitution about the
polyhedral core is increased [80, 81], see Fig. 24.
2.3
Effect of Incompletion of Outer Shell or Generation
Often dendritic liquid crystals are assembled through the preparation of den-
drons, and then the dendrons are attached to a central scaffold of a suitable
generation number. This technique allows for the dendrons to be prepared
on a large scale and then the attachments to the scaffold are done in smaller
number than if the mesogens are directly attached. However, one problem
that is sometimes encountered in this synthetic approach is that the scaffold
becomes progressively crowded as the dendrons are attached, and sometimes
this can lead to incomplete derivatization. In the following section, complete
and incomplete substitutions are investigated and compared.
Firstly, however, we can compare the attachment of dendron carrying ei-
ther terminally or laterally appended mesogens. Although the scaffold in this
example is a first-generation system based on pentaerythritol, the dendrimer
was in fact prepared from dendrons based on pentaerythritol, which were