Branching by the wrong addition of monomer or initiator

Trossarelli et al. studied the formation of poly-/ -alanine by the polymerization of acrylamide with ter/.-BuNa. The initiating anion is in equilibrium with the monomer [24] 

With chain growth, equilibrium (37) is shifted to the right so that all the initiator is consumed at the initial stages of polymerization. The growing anions can react even with incorporated double bonds. Simultaneously, the generated carbanion is isomerized by intra- or intermolecular transfer of H + to an nitrogen anion o 

The number of branching sites rapidly increases at first, but the rate decreases with conversion. 

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