Polyaromatic quinone diimines: A novel family of polymers

Abstract

Polyaniline has attracted much interest due to its unusual physical properties. A polycondensation route to polyanilines is a desirable alternative to the currently used non-discriminating oxidative polymerization. The oxidative synthesis does not allow structural diversity in the monomer and the polymer's structure is not well defined. A synthetic route to polyanthraquinone diimines was recently developed in this laboratory. These pernigraniline analogs are similar in structure to the fully oxidized polyaniline and may display electrical conductivity and optoelectronic properties. The aim of the current study was to investigate the incorporation of solubilizing substituents into the polyquinone diimine backbone, determine the molecular dynamics and microstructure of the polyquinone diimine through the use of model compounds, and reduce the polyquinone diimines to the emeraldine oxidation level. This dissertation accomplished the condensation polymerization of 1,5-di(oligo-(ethyleneoxy)) anthraquinones (EOn n = 1-3) and 1,4-, 1,5-, and 2,6-dioctyloxy-anthraquinones with both phenylenediamine and 4,4'-thiodianiline. Higher molecular weights were accomplished due to increased solubility. The polymers' microstructure and molecular dynamics were determined by X-ray crystallographic structure analysis and through NMR studies of model compounds. Model compounds and polymers were reduced by a hydrazine reduction method. Stereoregular polymers with molecular weights Mw, of 30,000 were obtained with 4,4'-thiodianiline and polymers having Mw 10,000-20,000 were obtained with phenylene-diamine. Model compounds were synthesized from aniline and the corresponding anthraquinone to provide structural characterization for the polymers. The model compounds revealed that an anti configuration is obtained with 1,5-disubstituted anthraquinones, while a syn configuration is obtained with 1,4-disubstituted anthraquinones. X-Ray crystal structure determinations were essential in determining the conformations of the model compounds. Variable temperature NMR studies gave detailed information about the molecular dynamics of the polymer chains for all polyquinone diimines. A syn/anti-isomerization was identified for unhindered anthraquinone diimines and a unique butterfly inversion was discovered for all anthraquinone diimines. A reduction method using hydrazine and palladium was applied to the reduction of quinone diimines to produce the corresponding diamines. Polymer studies indicate no generation of an emeraldine analog upon reduction. 2,6- and 2,5-Dimethyl and 2,3,5,6-tetramethyl benzoquinones were investigated as alternative quinones for obtaining emeraldine analogs.