INVESTIGATION OF RARE PHASE TRANSITIONS BY DENSITY MEASUREMENTS

Abstract

We report here the study of nature of few rare phase transitions viz., Isotropic ‒ Sm C, Sm C ‒ Sm F and Srn A ‒ Sm F transition in two homologues of α, ω-bis(4-n-alkylanilinebenzylid- ine-4′-oxy)alkane series using density measurements. Compound 10.040.10 exhibits Iso- tropic ‒ Sm C, Sm C ‒ Sm F and Sm F ‒ Crystal phase transitions. Whereas 10.0100.10 exhibits Isotropic ‒ Sm A, Sm A ‒ Sm F and Sm F ‒ Crystal transitions. Variation of density with temperature across the phase transitions Isotropic ‒ Sm A, Isotropic ‒ Sm C, Sm C ‒ Sm F and Sm A ‒ Sm F show a jump in density confirming that all these transitions are first order in nature. However, the magnitude of the density jump is smaller than expected at some of these transitions. The calculated pressure dependence of transition temperature is also reported.

Key Words:

• Symmetric liquid crystal dimers
• I-S_A transition
• I-S_C transition
• S_A−S_F transition
• S_C−S _F transition