Molecular Weight Distributions in Emulsion Polymerizations: Evidence for Coagulative Nucleation

Abstract

An examination of the number molecular weight distribution from emulsion polymerizations, obtained by using gel permeation chromatography, shows that, at low conversion, a distinct maximum is present at low molecular weights, while at higher molecular weights the distribution is exponential with decay constant given by the ratio of the rate coefficients of propagation and transfer. The maximum is attributed to coagulation of precursor particles during particle formation.