Liquid crystalline silicon-containing oligomers

Liquid crystalline siloxane oligomers with the same type of mesogenic groups (methoxyphenylbenzoate) but with different structures of siloxane cores (cyclooctasiloxane ring or octakissilsesquioxane cage) were synthesized. The set of oligomers with the same type of mesogenic groups but with different structure of siloxane cores gave a unique opportunity to study LC properties and structure relationships. The chemical structures of all compounds were confirmed using FTIR and 1H NMR and 29Si NMR spectroscopy. The thermal behaviour and the mesogenic properties of the siloxane oligomers were investigated using differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray diffraction. The mesogenic properties of side-chain liquid crystalline siloxane oligomers were discussed.