Phase Transition and Liquid Crystalline Structures of Side-Chain Liquid-Crystalline Polysiloxanes Containing Acetoyl Group as a Mesogenic Terminal Substituent

Polysiloxanes containing acetoy group as a mesogenic terminal substituent were synthesized and the effects of acetoyl group on liquid crystalline properties and structures were investigated. The poly[{ω-{4-(4-(acetoyl)phenoxy carbonyl)phenoxy}}alkyl methyl siloxanes] with different spacer lengths indicate smectic phases in the temperature range between glass transition (Tg) and isotropic phase transition (Ti). Smectic A (SA) phase was observed in each polymer, and additional smectic phase appeared under the SA phase as spacer lengths increased. The higher ordered smectic phase could be assigned to smectic E-like phase from the X-ray scattering results. The Ti’s, enthalpy and entropy changes of the polymers exhibited clearly odd-even effects.