Linear and crosslinked silicon based liquid crystalline materials

In this paper the effect of steric hindrance, crosslinking and the use of multipode mesogenic moieties is presented as a part of studies directed on the architectural modification of silicon containing SLCP's. Trist(trimethylsilyl)methyl(trisyl) groups have been attached to liquid crystalline comb-like polysiloxanes by hydrosilylation reaction in order to increase their thermal stability. It was found that attaching trisyl group to 10% of monomeric units led to a decrease in mass loss at 330°C by a factor of 2. The thermo-optical studies of linear and crosslinked LC polycarbosilanes exhibiting SmC* phase proved that crosslinking stabilizes the generated mesophases, especially during isotropisation process. The new synthetic route for polysiloxanes with pendant "triple-fork" mesogenes has been developed. It was found that such the structures are able to generate stable mesophases even if their molecular mass is relatively low.