Conformational phase transitions and re-entrance phenomena in dendromesogens

We investigate theoretically the liquid crystalline phase behaviour of glob ular dendrimers consisting of a soft inner scaffold and peripheral mesogeni c units attached to the scaffold by means of flexible chains. We use a gene ralised Onsager molecular theory to analyse model systems exhibiting confor mational rod-sphere and rod-disc interconversions. Phase transitions normal ly not encountered in low molar mass mesogens are reported. For a system wi th spherical lowest energy conformation a thermotropic re-entrance to the i sotropic phase is observed.