Communication: The propagation rate coefficient (k(p)) of methyl methacryla
te has been measured in miniemulsions. The molecular weight distributions s
how many higher order peaks which seems to be specific for pulsed initiatio
n polymerization in compartmentalized liquids. The k(p) values are ver simi
lar to bulk values although a frequency dependence is observed. This freque
ncy dependence, which was overlooked in earlier research, is also present i
n pulsed laser experiments in bulk.