LIQUID-CRYSTALLINE BEHAVIORS OF CONDUCTING POLYACETYLENE DERIVATIVE WITH MESOGENIC SUBSTITUENT AND ITS MIXTURE WITH FERROELECTRIC LIQUID-CRYSTAL

Liquid crystalline behavior has been studied in a polyacetylene deriva tive substituted with long side chains containing phenylcyclohexyl mes ogenic units such as poly (p-(trans-4'-n-octylcyclohexyl)phenoxy)-1-pe ntyne] (PPCH803A). A texture typical of smectic liquid crystal has bee n observed using an optical microscope. The smectic layer structure ha s also been confirmed by X-ray diffraction. Anisotropy of the optical absorption spectrum of the smectic phase; which is consistent with the results of the X-ray diffraction measurements, has been observed. The band gap of PPCH803A in the liquid crystalline phase has been evaluat ed as 2.9 eV, which is smaller than that in the isotropic liquid phase . The dielectric constant of PPCH803A changes stepwise at the phase tr ansition temperatures. A mixture of PPCH803A with, a ferroelectric liq uid crystal of low molecular weight exhibits a large dielectric consta nt and unique ferroelectric behavior.