PHASE-TRANSITION AND LIQUID-CRYSTALLINE STRUCTURES OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING ACETOYL GROUP-A MESOGENIC TERMINAL SUBSTITUENT

Polysiloxanes containing acetoy group as a mesogenic terminal substitu ent were synthesized and the effects of acetoyl group on liquid crysta lline properties and structures were investigated. The poly[{omega-{4- (4-(acetoyl)phenoxy carbonyl)phenoxy}}alkyl methyl siloxanes] with dif ferent spacer lengths indicate smectic phases in the temperature range between glass transition (T-g and isotropic phase transition (T-i). S mectic A (S-A) phase was observed in each polymer, and additional smec tic phase appeared under the S-A phase as spacer lengths increased. Th e higher ordered smectic phase could be assigned to smectic E-like pha se from the X-ray scattering results. The T-i's, enthalpy and entropy changes of the polymers exhibited clearly odd-even effects.