Effect of concentration and temperature on the properties of the microspheres prepared using an emulsion–solvent extraction process

Methylaluminoaxane (MAO) microspheres of average size smaller than 100 μm were prepared using a solvent extraction process; excess of perfluorocarbon (PFC) was added to the hydrocarbon-in-perfluorocarbon emulsion to solidify the MAO droplets. The effect of the MAO concentration in the dispersed phase, the temperature of the PFC added to the emulsion and the preparation temperature on the size, the size distribution and the morphology of the MAO microspheres was studied. MAO droplets broke up more easily with decreasing dispersed phase viscosity and hence the size of the MAO microspheres decreased. The temperature of the PFC added to the emulsion did not significantly affect the size and the morphology of the MAO microspheres. The size of the MAO microspheres increased with increasing preparation temperature. The main reason for the increased size of the MAO microspheres was the increased coalescence with increasing preparation temperature. In addition the porosity of the MAO microspheres increased with increasing preparation temperature.

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► Microspheres were prepared using an emulsion–solvent extraction process.
► A hydrocarbon-in-perfluorocarbon emulsion was used.
► Size of microspheres decreased with decreasing dispersed phase viscosity.
► Size of microspheres increased with increasing preparation temperature.
► Porosity of microspheres increased with increasing preparation temperature.