To tilt or not to tilt? Kinetics of structure formation in a discotic liquid crystal

Abstract

The distinctly different unit cells, dipolar dynamics and viscoelastic properties of the two columnar phases in a dipole-functionalized discotic liquid crystal (mono-iodine hexa-peri-hexabenzocoronene) were employed as fingerprints and allowed investigating the kinetic pathways towards formation of the crystalline phase. X-Ray scattering, dielectric spectroscopy and rheology revealed a nucleation and growth process. The transformation involved coexisting unit cells composed from columns with either tilted or non-tilted disks and the absence of intermediate states. The transition can be described as a transformation from a structurally weakly ordered but dipolar well-ordered liquid crystalline phase to a structurally well-ordered but dipolar disordered crystalline phase.