Phase behavior and blue-phase-III-isotropic critical point in (R)-(S) mixtures of a chiral liquid crystal with a direct twist-grain-boundary to blue-phase transition

摘要: We have investigated mixtures of the (R) and (S) enantiomers a chiral liquid crystal, (R)- or (S)-1-methylheptyl 3'-fluoro-4'-(3-fluoro-4-octadecyloxybenzoyloxy)tolane-4-carboxylate using high-resolution adiabatic scanning calorimetry. The pure compound has direct transition from twist-grain-boundary to blue phase without an intermediary nematic phase. For phases different kind behavior as function enantiomeric excess is observed, most probably related presence twist-grain-boundary-A instead below phases. general form this diagram compared with traditional blue-phase behavior. Furthermore blue-phase-III-isotropic critical point, analoguous that liquid-gas system, consistent experimental theoretical work recently published in field. Finally, effect changing on latent heats first order transitions measured discussed.