Nucleation loci in the ring-opening polymerization of octamethyl- cyclo-tetrasiloxane in Winsor I system with dodecylbenzene sulfonic acid sodium salt and sulfuric acid

The ring-opening polymerization of octamethylcyclotetrasiloxane (OTS) was carried out in an Winsor I system with dodecylbenzene sulfonic acid, sodium salt (DBSNa) as emulsifier and sulfuric acid as initiator, to clarify the mechanism of the polymerization, especially focusing on the nucleation loci, the rate of generation of nonvolatile molecules and the average diameter of generated polymer droplets. In the system where DBSNa concentration is higher than the critical micellar concentration (CMC), nonvolatile molecules were generated in the aqueous phase and their generation rate became higher with an increase in DBSNa concentration, while nonvolatile molecules were not generated at emulsifier concentrations lower than the CMC. These experimental results support that nucleation did not take place in the true aqueous phase, but originated from the micelles.