Dielectric and Kerr Effect Studies of Electro-Active Polymer Complexes

Abstract

Samples of polyphenylenes have been prepared from benzene, biphenyl and 1,4-dibromobenzene using a variety of synthetic procedures. The nature and composition of the polymers has been studied indirectly by solvent extraction of low-molecular weight material. Chromatographic techniques have shown that a major proportion of this material is comprised of para-substituted oligophenylenes. The reduction coupling of benzene has been found to yield a great variety of polyaryl compounds in addition to para-substituted polyphenylenes. The polymerization of biphenyl in solution in cyclohexane using AlCl₃/CuCl₂ catalysts gave predominantly para-substituted polyphenylenes and relatively large amounts of the odd-membered oligomers. A reaction scheme has been prepared to account for these observations. The dielectric and electro-optical properties of tetracyanoquinodimethane and iodine complexes of benzene, toluene, o-, m-, p-xylene, biphenyl, terphenyl and m-biphenylbenzene and those of the pure compounds were undertaken through the measurement of static dielectric permittivities and Kerr constants. Experimental molar Kerr constants have been derived for the complexes and compared to theoretical values calculated using bond and group polarizabilities taken from the literature. The experimental molar Kerr constants were in general considerably larger than the corresponding theoretical values and these differences were attributed to either increases in polarizability and/or increases in the anisotropy of polarizability of the complexes. The effects of exaltation on the magnitudes of the molar Kerr constants have also been considered. Kerr effect and dielectric studies have also been carried out on complexes formed between tetracyanoquinodimethane and different stereoregular forms of poly(N-vinylcarbazole) in solution in 1,4-dioxane. The magnitude of the Kerr effect was found to vary with changes in tacticity for the range of molecular weights and molecular weight distributions considered in this study.