25067-59-8

Preparation

N-Vinyl carbazole may be obtained from phenylhydrazine and cyclohexanone by the following route:The second step in this synthesis is an example of the Fischer indole synthesis. Carbazole also occurs in coal tar. Poly(vinyl carbazole) is produced by adiabatic bulk polymerization under nitrogen pressure using azobisisobutyronitrile and di-tert-butyl peroxide as initiators. Heating to 80-90°C causes an onset of polymerization and a rapid increase in temperature. After the maximum temperature has been reached the mass is cooled under pressure.Poly(vinyl carbazole) is a very brittle material with a high softening point (about 195°C Vicat). It is insoluble in most organic solvents except aromatic and chlorinated hydrocarbons and tetrahydrofuran. The polymer is difficult to mould, requiring high process temperatures, namely about 300°C for injection moulding and 250°C for compression moulding. More usually the material is cast as thin film from solution. The most significant property of poly(vinyl carbazole) is its high photoconductivity and this has resulted in widespread use of the polymer in electrostatic dry-copying machines. When an electrostatic charge is applied to the polymer in the dark it discharges to an equilibrium value but when the polymer is illuminated almost complete discharging occurs. This phenomenon is used to create a latent electrostatic image which is then developed by transferring the charge to the toner. Poly(vinyl carbazole) also has good electrical insulation characteristics which are maintained over a wide range of temperature and frequency. On account of these characteristics, the polymer has been used as a capacitor dielectric, but this application is now of minor importance.

Purification Methods

Precipitate it seven times from tetrahydrofuran with MeOH, with final freeze-drying from *benzene. Dry it under vacuum.

Definition

ChEBI: A macromolecule composed of repeating 9-ethylcarbazole units.

General Description

Poly(9-vinylcarbazole) (PVK) is a conductive polymer which is mainly used as a hole transporting medium at high efficiencies with low driving voltage. It can also be used as an anode for hole injection and can act as an effective charge transferring gate by co-doping it with organic dyes.