Studies of phase diagram of a liquid crystal with 4-[2-(3-fluorophenyl) ethyl]biphenyl core of molecules

Abstract

Basing on the results of differential scanning calorimetry and transmitted light intensity methods and texture observations in the temperature range from-50 °C to 90 °C phase diagram of 1-[3-fluoro-4-(1- methylheptyloxycarbonyl) phenyl]-2-[4'-(2,2,3,3,4,4,4-heptafluorobutoxybutoxy) biphenyl-4-yl]ethane was established. Monotropic system of thermodynamic phases was found. On cooling the isotropic phase transforms at 85°C to ferroelectric SmC* phase and further two liquid crystalline phases, antiferroelectric SmC*A and SmI, and a metastable crystal Cr2 reveal. During heating exothermic anomaly in the wide temperature range was observed and ascribed to evolution of Cr2 to the stable crystal Cr1. On further heating both SmC*A and SmC* phases were observed. Thermodynamic parameters were calculated for all phase transitions. During rapid cooling (10 K/min) vitrification of metastable Cr2 crystal at Tg =-115 °C was registered.