Induced Smectic Mesomorphism in Mixtures of p-Cyano-p'-pentylbiphenyl and p-Pentylbenzoic Acid

Abstract

The phase diagram of p-cyano-p'-pentylbiphenyl (CPB) and p-pentylbenzoic acid (5BA) shows a maximum value of the nematic-isotropic transition temperature at ∼equimolar concentrations of CPB and the dimer of 5BA (D5BA). Two eutectic points occur at concentrations of D5BA of 8 and 65 mole %, respectively, and an induced smectic phase occurs in the concentration range of 15 to 65 % D5BA. Dielectric properties and the spontaneous homeotropy of some of the mixtures can best be understood by considering the phases to consist primarily of D5BA and CPB, with a small amount of free 5BA modulating the dielectric properties and promoting homeotropic alignment.