Diagnosis of Living Polymerization

For example, the rate of initiation may be slow relative to that of propagation, in which case the MWD will tend to become broader. If ion-generation is slow, the effects of chain transfer to initiator and slow initiation may overlap and may not even be distinguishable. Chain transfer to monomer, initiation by protic impurity ( H20 ), etc., may be present which will further complicate the synthesis of uniform predetermined molecular weight polymers. 

The effect of unwanted reactions may be compensatory. For example, both chain transfer to monomer and initiation by H20 increase the number of macromolecules (N) and give rise to lower than theoretical molecular weights whereas slow initiation broadens MWD, since N is smaller than the initiator concentration I0 and not constant. 

Many authors have dealt with such problems and have tried to develop analytical methods for the diagnosis of living polymerizations [1,19,20,21,24, 29,30,45,51,55-57]. For example, the most recent effort is due to Penczek et al. [21] who combined the M vs Wp (molecular wieights vs weight of polymer produced) and — ln(l — C) vs t (rate of polymerization vs time) plots and expressed conversion (C) as a function of the degree of polymerization (DPn)  

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