Modeling polystyrene homogeneous-coagulative nucleation in Pickering emulsion polymerization
Abstract
Investigation of particle nucleation in surfactant-free emulsion polymerization of styrene using Laponite clay as Pickering stabilizer is considered. The effective number of clay platelets contributing to the surface charge of the polymer particles was calculated, and used to estimate their stabilizing efficiency. A coagulative nucleation mechanism was proposed and the coagulation coefficient was calculated using the DLVO theory. The Hamaker constant involved in the attractive potential of the clay-polymer composite particles was measured experimentally. The model was found to fit the experimental data in terms of the number of nucleated particles and the nucleation period. The effective number of clay platelets contributing to the surface charge was found higher than the number of platelets allowing full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation required almost complete coverage.
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