Polymerization of 3, 6-dibromo-9-(2, 3-epoxypropy) carbazole with triphenylcarbenium salts

Abstract

Cationic polymerization of 3,6-dibromo-9-(2,3-epoxypropyl)carbazole with triphenylcarbenium salts (triphenylcarbenium hexachloroantimonate, triphenylcarbenium tetrafluoroborate and triphenylcarbenium pentachlorostannate) has been studied by a microcalorimetric technique. Acceleration of polymerization after reaching about 70% conversion of the monomer has been observed. The onset of acceleration coincides with the beginning of the linear increase of M(n)BAR with conversion and with the moment when the concentration of OH-groups in the reaction mixture becomes constant. The observed phenomena are explained by the change of polymerization mechanism from the conventional active chain-end mechanism to the activated monomer mechanism. After complete conversion of the monomer, polymerization mixtures can be used for the casting of electrophotographic layers in which the residual catalyst acts as sensitizer. Such layers exhibit high photoconductivity in the visible region.