Molecular iodine as an initiator

Polymerization of vinyl monomers 6.1 MOLECULAR IODINE AS AN INITIATOR 

Molecular iodine was shown to be an effective initiator of the polymerization of active olefins (e.g. alkyl vinyl ethers) as long ago as 1878 [52]. The mechanism operative is now accepted as being a cationic one, and a number of kinetic investigations have been carried out from time to time 153—58]. In addition parallel ultraviolet/visible spectro- 

It was postulated that free iodine could react with a monomer molecule to form a 7r-complex, or an active centre capable of propagating, i.e., 

Two additional assumptions were made, firstly the complex was inactive and could not initiate polymerization, secondly termination was a simple unimolecular process. The propagation and termination steps could therefore be written as 

Alternative schemes of initiation were considered only in a qualitative manner. 

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