キュービック液晶1,2-bis-[4-(n-alkoxy)benzoyl]hydrazineの熱容量と相転移

抄録

Heat capacities of 1,2-bis-[4-(n-octyloxy)benzoyl]hydrazine were measured with an adiabatic calorimeter in the 13-450 K range. Four phase transitions were observed at T=392.3 K(Crystal II→Crystal I), 404.4(Crystal I→Cubic phase), 417(Cubic phase→Smectic C) and 425(Smectic C→Isotropic Liquid). Of the total transition entropy, about 90 per cent is gained at the crystal-to-crystal transition and the melting, indicating that the cubic phase is characteristic of a mesoscopic state. This large transition entropy is well interpreted in terms of disordering due to conversion between the trans and gauche comformations of the n-alkyl moieties.