MODIFICATION OF POLY(PARA-PHENYLENE VINYLENE) BY INTRODUCTION OF AROMATIC-GROUPS ON THE OLEFINIC CARBONS

Abstract

Nine poly(arylene alkenylenes) with phenyl, thienyl and furanyl substituents on ethenylenic or butadienylenic links were synthesized: one via dehydrohalogenation, the others via Horner-Wadsworth-Emmons reactions. For the latter approach five new diketones of type aryl-CO-aryl-CO-aryl and aryl-CO-CH=CH-aryl-CH=CH-CO-aryl were prepared. In addition 1,4-bis(2,2-diphenyletheriyl)benzene (1a) and 1,4-bis[2-(p-tolyl)-2-phenylethenyl]benzene (2a) were made to serve as model compounds. All materials were characterized by NMR, IR and mass spectroscopy. The polymers are soluble in CHCl3, allowing the determination of the molecular weight distribution by GPC and the preparation of films. The latter were doped by iodine vapour to give d.c. conductivities of about 10(-10) S cm-1 for the substituted ethenylenes and about 10(-4) S cm-1 for the substituted butadienylenes. The results suggest large deviations from planarity in the ethenylenes, which is corroborated by the NMR behaviour of 1a. Complete shift assignments are given of C-13 spectra of 1a and 2a, proving that 1a is conformationally homogeneous, but that 2a is synthesized as a statistical mixture of three configurations.