Development of Molecular Weight Distribution in ATRP with Radical Termination

In a previous work, a model of full molecular weight distribution (MWD) for atom transfer radical polymerization with radical termination has been developed, using analogy to a series of continuous stirred tank reactors. This model assumes constant reaction rates, which is applicable to low conversion batches or steady‐state continuous processes. In this work, the model is generalized to any polymerization condition, which provides variations of the reaction rates with conversion are known. Using this extended model, the effect of monomer conversion on the MWD is demonstrated, for the cases with and without radical termination. The conversion dependence of MWD is found to be significant. The broadening of distribution is correlated to the lack of control and/or the loss of livingness. Both control and livingness are necessary conditions for narrow MWD. It is also found that the effects of these two factors are very different, yielding different distribution shapes, even with similar average chain lengths ( r N ) and polydispersity indexes (PDI).