Cationic polymerization of N-vinyl carbazole by trityl salts—I.: Reactivity of propagating species

The cationic polymerization of N-vinyl carbazole, initiated by Ph₃C⁺ AsF₆^? and Ph₃C⁺ PF₆^? in methylene dichloride at 20 and 0°, has been studied in some detail. Reactions were very fast and rates of monomer consumption were measured using an adiabatic calorimetric technique. Initiation was relatively “slow” but complete, and termination was deduced to be insignificant during kinetic lifetimes. Values for k_p were found to vary with the initial initiator concentration; this dependence is discussed in terms of current theories regarding equilibria between ion pairs and free ions in non-aqueous solvents. k_p⁺ values estimated from two methods of extrapolation are 9.5 · 10⁵ M^?1 sec^?1 at 20° and 4.8 · 10⁵ M^?1 sec^?1 at 0°. Finally, it has been found that ion pairs are much less reactive than free ions in this system.