Kinetics of ring-opening polymerization of octamethylcyclotetrasiloxane in microemulsion

Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane (D4) in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassium hydrate as an initiator. The particle size was determined by the dynamic light scattering (DLS) technique and the reaction rates of the polymerization were discussed. Furthermore, the kinetics was studied by an initial-rate method, and the effects of the monomer, emulsifier and initiator concentrations and the temperature on polymerization conversions were investigated. From the kinetic results, the rate of polymerization, R-p at 80 degrees C can be expressed as R-p = k[D4](0.79)[OTAC](0.64)[KOH](0.38) and the apparent activation energy (E-a), which was determined by half-period method, is 95.32 kJ mol(-1). (C) 2013 Min-Min Shen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.