Anionic polymerization mechanism termination process absence

Chain transfer reactions are considered here irrespective of the exact chemical mechanisms of transfer that are discussed in detail, for example, in the comprehensive review of Glasse [9]. It should be stressed that all calculations were performed bearing in mind anionic polymerization, so the main concern in all theoretical papers reviewed is the absence of kinetic termination rather than the anionic mechanism of chain propagation. Thus, the conclusions drawn are valid for all processes that satisfy this condition. 

A chain reaction without termination produces so-called living polymers. Even if on polymerization the initial monomer is used up, a new monomer can be added in a second step and the polymerization restarted as long as the active sites are not destroyed. The reaction became possible when initiation of vinyl polymerization with anionic mechanism was discovered by Szwarc in 1956 [19]. The process is easy to understand. A fixed number of initiator molecules, N, is added to the monomer under conditions that eliminate termination (i.e., in the absence of water and oxygen). Figure 3.31 illustrates living polymerization with 10 initiator and 42 monomer molecules. Without termination, the reaction stops when all monomers are used up. 

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