The anionic polymerization of cyclosiloxane in aqueous emulsion was performed with octamethylcyclotetrasiloxane(D4) as monomer and benzyldimethyldodecylammonium hydroxide (BDAH) as catalyst and emulsifying agent.The innovation of this study includes:(1) Based on the analysis of elementary reaction

the forming mechanism of concentration of active center was proposed.(2) The changing rule of the concentration of active centers with reaction was quantitatively obtained according to the generalized kinetic model of ring_opening polymerization of cyclosiloxanes.Emulsion polymerization recipe used in this study consists of octamethylcyclotetrasiloxane

benzyldimethyldodecylammonium hydroxide and water. All materials were heated up to reaction temperature (wmonomer∶wBDAH∶wwater=33∶1∶66).The mixture was then homogenized for 1 min to obtain emulsion.The emulsion was transferred to a glass reactor

and nitrogen was bubbled through the solution.The reaction temperature was adjusted with a constant temperature water bath.The polymerization was carried out under mechanical stirring (200 r/min).A certain amout of reactant was taken out during the course of polymerization and neutralized with glacial acetic acid to a pH near 8 in order to stop the reaction

and then used for measuring the needed data.The bulk polymerization of cyclosiloxane was performed with octamethylcyclotetrasiloxane (D4) as monomer and benzyldimethyldodecylammonium hydroxide as catalyst.And the sample was periodically taken out for conversion measurements.The anionic polymerization of cyclosiloxane in aqueous emulsion was performed.The conversion and the molecular weight of synthesized polymer were examined by gel permeation chromatography (GPC).The forming mechanism of concentration of active center was proposed

and the changing rule of the concentration of active centers with reaction was quantitatively obtained.The results show that the concentration of active center gradually increases to a steady state when the temperature is relatively low

and that the concentration of active center only increases monotonously with time when the temperature is relatively high.