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 80-90C 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 195C 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 300C for
injection moulding and 250C 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.
