Mechanical Rotor Model for Fluorinated Terphenyl Liquid Crystals

A mechanical model is established to explain phase behaviors and thermal properties of liquid crystals (LCs). We postulate that LC phases are micro-machine systems consisting of an ensemble of molecular rotors. The phenomena of the thermal stability of phase and polymorphism are interpreted in terms of mechanics that involve basic parameters such as center of gravity (G), moment of inertia (I A), eccentricity (ε) and mass deviation along the molecular axis (δ). A novel concept of “slim isomer” and “fat isomer” for the fluorinated LC system is proposed. Furthermore, the parameter ωc, critical rotational velocity around the long molecular axis is adopted to analyze the thermal stability at the critical point. It is determined that the value of ωc is a key parameter for the characterization of each homologous series.