Cationic heterocyclic polymerization Initiation mechanism

Ionic Polymerization Ionic chain polymerizations can also be initiated with the aid of Vis/UV light although, as in the case of free-radical photopolymerization, the light serves only as an initiating tool. Most studies on ionic photopolymerization have focused on cationic polymerization, which proceeds rapidly and is not inhibited by oxygen [18,21-24]. Moreover, cationic photopolymerization is apt to polymerize monomers such as vinyl ethers, oxiranes (epoxides), and other heterocyclic compounds that do not polymerize via a free-radical mechanism (Table 3.9). 

Butler s successful demonstration of the existence of the intra-intermolecular polymerization mechanism triggered widespread research in this area. As a result, excellent procedures for this type of ring-forming polymerization evolved. Cyclopolymerizations can take place by free-radical, cationic, anionic, Ziegler, and other types of initiations. These various types of intra-intermolecular polymerizations are discussed below. Only all-carbon ring-containing polymers are covered. The formation of heterocyclic polymers by this reaction will be discussed in a forthcoming volume (Part B). 

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