INFLUENCE OF THE METAL-CROSS-LINKING ON THE DIELECTRIC, MECHANICAL, AND THERMAL-PROPERTIES OF A LIQUID-CRYSTALLINE POLYAZOMETHINE

Cross-linked polymeric materials have been synthesized by copper(II) c omplexation of a semiflexible main-chain liquid crystalline polyazomet hine. The influence of the copper(II) cross-linking density on the the rmal properties has been studied by DSC. The relaxation behavior of bo th the parent polymer and the complexed polymers has been investigated by dielectric spectroscopy and dynamic mechanical measurements. The p arent compound exhibits three-relaxations (denoted by alpha, beta, and gamma), together with a conductive process at low frequency. The rela xations have been associated with the glass transition (alpha), rotati onal motions located in the rigid mesogenic core (beta), and local mot ions of the decamethylene flexible spacer (gamma). Semiempirical calcu lations have been carried out in order to evaluate the rotational ener gy barriers which can account for the beta process. The influence of t he degree of crosslinking on the activation energies and on the streng th and shape parameters has also been studied in the copper(II)-comple xed polymers.