Broadband Dielectric Spectroscopy on Ferroelectric Liquid Crystalline Polymers

Abstract

The collective and molecular dynamics of ferroelectric liquid crystalline side group polasiloxanes has been investigated be use of broadband dielectric spectroscopy (10⁻²Hz – 10⁹Hz). In the lower frequency range (>10⁶Hz) two collective relaxations, Goldstone - and soft - mode, could be observed. They are assigned to the fluctuations of the phase and the amplitude of the helical superstructue, respectively. In the high frequency regime (10⁶Hz – 10⁹Hz) one dielectric relaxation, the ᵬ - relaxation, is found. It is assigned to the hindered rotation (libration) of the mesogene around its long molecular axis. It shows an Arrhenius - like temperature dependence with no deviations at the phase transition S _A /S* _C . A dilution of the mesogenes causes a decrease of the collectivity but remains the local dynamics uninfluenced.