Quantitative affinity cleavage

The initiation reaction comprises the nucleophihc attack of the initiator at the carbonyl carbon, followed by an acyl-oxygen cleavage and formation of the active species, an alcoholate [24]. The efficiency of the initiation depends on the nucleophi-Hcity of the initiator and on the electron affinity of the monomer if both are high, then initiation is both fast and quantitative. A slow initiation leads to a broadening of the molecular weight distribution and a loss of molecular weight control. 

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