Phase Behavior and Phase Structures of Hexa-n-octoxyl-triphenylene
Abstract
Since the discovery of discotic liquid crystals and their columnar phases in 1977, a large amount of attention has been paid to this special liquid crystal family because of its application potential in photonic and electronic areas. As a disk-like liquid crystal, hexa-n-octoxyl-triphenylene was studied on its phase behavior and identification of phase structures. Differential scanning calorimetry, x-ray diffraction and transition electron microscopy results show that, in addition to the hexagonal columnar liquid crystalline phase (Fh) at high temperature, two orthorhombic crystalline phases (K2, K3) and a triclinic crystalline phase K1, were also observed at relatively lower temperature. The K1 phase was obtained by quenching the sample from its Fh phase. Slowly cooling from Fh phase led to the formation of the K2 phase. Both the K1 and K2 phases could melt upon heating procedure and recrystalize to form the K3 phase. Fh could be obtained by cooling the material from its isotropic melting state or heating K3 phase to 57°C temperature. Either the K1 or K2 was metastable phase relative to the K3 phase, which is the most stable phase. The phase behavior was monotropic, because of bypass of the K3 phase upon cooling.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARB33017J