3C13 Heat Capacity of Isotropic Mesogen, ACBC (16)

Abstract

Heat capacity of isotropic mesogen ACBC (16) was measured by adiabatic calorimetry. Besides the known condensed phases, a new crystalline phase was found to undergo a glass transition around 165 K. The first-order nature of the SmC-cubic phase transition at 431.15 K was confirmed through supercooling experiments. The entropy of this transition (Δ_<trs>S) lies on a straight extrapolating line of the chain-length vs Δ_<trs>S plot for the SmC - Im3m transition in ANBC, suggesting nearly the same core size for ANBC and ACBC. A broad hump in the C_p curve above the transition to isotropic liquid at 474.30 K was demonstrated to continue to a low-temperature side if the isotropic liquid was supercooled.