Models for First Shell Substitution Effect in Stepwise Polymerization

SARMORIA, C; MILLER, D R

MACROMOLECULES

American Chemical Society

Año: 1991 vol. 24 p. 1833 - 1845

0024-9297

We present a branching process model of stepwise homopolymerization with the first shell substitution effect (FSSE). Some authors have stated that branching process statistical models are not appropriate for certain nonideal (nonrandom) kinetically controlled polymerizations; a stepwise homopolymerization with FSSE is an example of such a polymerization. Alternate approaches to modeling these systems include Monte Carlo analysis and purely kinetic modeling. Our model is exact given the assumptions of multiplicative kinetic rates and no cyclization; its implementation has a small numerical error due to discretization. We compare its predictions with those of an exact kinetic model found in the literature. The results of the comparison confirm the validity of correctly defined statistical models for nonideal irreversible polymerizations. In order to be exact, statistical models for nonideal polymerizations must contain a sufficient level of structural detail. Aggregation of structural detail may lead to inexact models. We illustrate the consequences of aggregation and refinement of modeling detail with our FSSE homopolymerization model.