No abstract

End-group studies have been made on poly-N-vinylcarbazole prepared by polymerisation at 60°C in benzene with either azobisisobutyronitrile or benzoyl peroxide as initiator. The azo-nitrile gives polymers having on average 1.35 initiator fragments per molecule, suggesting that combination and disproportionation occur with approximately equal frequencies. The peroxide gives polymers of unexpectedly low molecular weight and having close to two initiator fragments per molecule ; benzoyloxy groups form a high proportion of these fragments. It appears that benzoyl peroxide does not promote a true radical polymerisation of N-vinylcarbazole,

The polymerization of N‐vinylcarbazole at 60°C in benzene has been initiated with azoisobutyronitrile, benzoyl peroxide, and their mixtures. The kinetics indicate that the azonitrile and the peroxide promote polymerizations of fundamentally different types. The resulting polymers have been examined by gel‐permeation chromatography. The polymer produced with benzoyl peroxide contains a small amount of a high molecular weight fraction which, from the point of view of end groups, resembles the polymer made by use of the azonitrile. It is concluded that benzoyl peroxide in this system gives rise to two types of polymerization which occur simultaneously.

Copolymers of N-vinylcarbazole (VCZ) with methyl methacrylate (MMA) and styrene (ST) were prepared using doubly-labelled benzoyl peroxide as initiator and the relative numbers of benzoyloxy and phenyl endgroups were determined. In the copolymers containing MMA, the ratios of the two types of end-group are those expected for products of free radical polymerization. The copolymers of VCZ with ST contain benzoyloxy and phenyl end-groups in proportions which correspond to those found in homopolymers ofVCZ made in non-radical polymerizations promoted by the peroxide.