Dielectric and C n.m.r. studies of various stereostructural forms of poly(N-vinyl carbazole)

Three different stereostructural forms of poly(N-vinyl carbazole) (PVK) have been prepared using cationic (AlCl₃ and BF₃(CH₂CH₃)₂O) and radical (azobisisobutyronitrile) initiators. The dipole moment per repeat unit of PVK has been determined and correlated with ¹³C n.m.r. spectra of the methine and methylene carbon absorptions for fractions of PVK in solution in 1,4-dioxan. The dielectric data for cationically prepared PVK appear to indicate a random coil configuration or possibly a rod-like structure in which the dipole moment vectors of the carbazole groups are randomly oriented but remain approximately perpendicular to the long axis of the molecule. For each type of PVK examined the repeat unit dipole moment was observed to be independent of molecular weight over the range 10⁴–10⁷ and insensitive to polydispersity.