Dielectric and 13C 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.