Assumption has been made on the mechanism of the cationic emulsion polymerization of octamethylcyclotetrasiloxane (D4). The ring opening of D4

the addition polymerization and the condensation reaction take place on the surface of emulsion particle. The molecular weight

the molecular weight distribution and the number of polymer molecules are dependant on the ratio of addition reaction to condensation

the ratio is controlled by the concentration of the emulsifier on the emulsion particle.