Molecular dynamics of a smectic liquid-crystalline side-chain polymer. The dielectric properties of aligned and nonaligned material studied over a wide range of frequency and temperature

The dielectric relaxation behavior of a nonaligned and an aligned liquid-crystalline (LC) polymer are reported for the ranges 10^?3.5 to 10⁵ Hz and 274–363 K. Multiple processes (δ and α) are observed that follow a Vogel equation for the temperature dependence related to the apparent glass transition temperature. The occurrence of these processes and the variation in their relaxation strengths as sample alignment is changed is interpreted in terms of a molecular theory for the dielectric behavior of a LC polymer that involves the director order parameter S_d, the mesophase order parameter S, the dipole moment components of the mesogenic head groups, and their associated relaxation functions.