Lactam , base catalyzed polymerization

In 1955, Monsanto Company began exploratory research on the base catalyzed polymerization of lactams. A two-stage mechanism for the thermally-initiated anionic polymerization was postulated as shown in Figure 1. This proposed mechanism was first published in Italian patent 580069 which was issued July 28, 1958. (2)... 

The subsequent mechanism of the base-catalyzed polymerization of caprolactam is complicated. Ring opening of the initiated monomer does not occur. Since the lactam anion is stabilized by resonance, viz.,... 

Note Examples include the base-catalyzed polymerization of lactams, the acid-catalyzed... 

An important consequence of these side reactions is the presence of water, irrespective of the fact that anionic polymerization starts in anhydrous conditions. Water is able to hydrolyze N-acyl lactams, p-ketoamides, p-ketoimides, and the imide branching points via fast base-catalyzed reactions. During these hydrolytic reactions, carboxylates, amine... 

The anionic polymerization of lactams is catalyzed by strong bases capable of forming lactam anions. In the presence of a suitable initiator such as an acyl lactam, a very fast reaction occurs at temperatures in the range of 100 C to 200°C. Without the initiator, polymerization temperatures appreciably above 200°C are necessary and a noticeable induction period is present. Anhydrous conditions are an essential pre-requisite for good yields and rates and reproductible results. The most relevant reactions in the activated polymerization of lactams are the following ones ... 

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