Liquid crystal system as molecular machinery: Investigation of dynamic impedance matching between molecular core and terminal groups using rotor-bearing model

Liquid crystal phase stability is examined for liquid crystal terphenyls an d their fluorinated derivatives, and some general rules are proposed that r elate phase stability to molecular structures. A mechanical model is applie d to explain the phase behaviours of these compounds. We postulate that liq uid crystal phases are micromachine systems consisting of an ensemble of mo lecular rotors. The molecular core and terminals are the rotor and axes, re spectively. The terminals also function as bearings for the subsequent laye r's molecular rotors. Phenomena of the thermal stability of phase and polym orphism are interpreted in terms of basic mechanical and dynamical paramete rs: centre of gravity, eccentricity, moment of inertia and mass distributio n. The importance of dynamic impedance matching between parts, rotors, axes and bearings, is emphasized. Fluorination effects on liquid crystallinity are explained in a unified manner on a mechanical and dynamical basis.