Production of Core–shell Particles by Combined Semibatch Emulsion/Suspension Polymerizations

Core–shell polymer particles were produced by combined semibatch emulsion/suspension polymerizations, using different monomers. It is shown that the morphology of the shell depends on the glass transition temperature (Tg) of the emulsified particles and that specific areas can vary considerably (7.9 to 37 m2 · g−1), depending on reaction conditions and used monomers. Particularly, a thin film is formed around the core when the Tg of the polymer that constitutes the shell is lower than the reaction temperature, while a porous shell is formed when the Tg of the polymer material is higher than the reaction temperature. Based on the observed data, a physical model was proposed to explain the formation of core–shell particles by combination of typical suspension and emulsion polymerization recipes. magnified image