Molecular dynamics of liquid crystalline side-chain oligoacrylates and oligomethacrylates with 4-cyanazobenzene side groups. Influence of external fields on dielectric properties

Dielectric behavior of several smectic side-chain oligoacrylates and oligom ethacrylates with 4-cyanazobenzene mesogenic side groups has been investiga ted. Below the glass transition temperature two relaxation regions of dipol e relaxation (the gamma(1) and the beta processes) caused by local mobility were detected. The molecular mobility of the gamma(1) process increases wi th spacer length but in the case of the beta process the mobility is nor ch anged. In the LC state, near Tp transition, two cooperative processes, alph a- and delta, related to the reorientation of transverse (mu(perpendicular to)) or longitudinal (mu(\)) components of the dipole moment of the mesogen ic group, respectively, were observed. The orientation in external electric or mechanic fields leads to the establishment of planar or homeotropic ori entation of mesogenic side groups.