Modeling Polystyrene Homogeneous-Coagulative Nucleation in Pickering Emulsion Polymerization

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 is calculated, and used to estimate their stabilizing efficiency. A coagulative nucleation mechanism is proposed and the coagulation coefficient is calculated using the Derjaguin-Landau-Verwey-Overbeek theory. The Hamaker constant involved in the attractive potential of the clay-polymer composite particles is measured experimentally. The model is 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 is found higher than the number of platelets allowing full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation requires almost complete coverage.

Automated summary

This study investigates particle nucleation in surfactant-free emulsion polymerization of styrene using Laponite clay as a Pickering stabilizer. The effective number of clay platelets contributing to the surface charge of the polymer particles is calculated to estimate their stabilizing efficiency. A coagulative nucleation mechanism is proposed, and the coagulation coefficient is calculated using the Derjaguin-Landau-Verwey-Overbeek theory. The Hamaker constant involved in the attractive potential of the clay-polymer composite particles is measured experimentally. The model fits the experimental data regarding the number of nucleated particles and the nucleation period. It is found that a higher effective number of clay platelets is needed for surface charge than for full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation requires almost complete coverage.