Density studies of two dimeric liquid crystals of the ?±,??-bis-(4-n-alkylaniline benzylidene-4a??-oxy) alkanes series

摘要

As a part of our systematic study of symmetric liquid crystal dimer homologous series, α,ω-bis-(4-n-alkylaniline benzylidene-4’-oxy) alkanes, we report here the nature of different phase transitions exhibited by two of these dimers using density measurements as a function of temperature. The compound 7.O12O.7 exhibits only nematic phase; whereas 8.O12O.8 exhibits smectic G phase. The phase transitions studied viz., isotropic – nematic (Iâ????N) and the rare transition i.e., isotropic – smectic G (Iâ????SmG), are confirmed to be of first order nature. We also report here the calculated density jumps, thermal expansion coefficients and pressure dependence of transition temperatures which are analyzed in the light of available literature data.