Morphology and particle size distribution controls of droplet-to- macroporous/hollow particles formation in spray drying process of colloidal mixtures precursor

The morphology control of droplet-to-macroporous/hollow particles formation using an ultrasonically spray-drying method as well as correlation between the droplet and particle size distribution of generated particles using a precursor of colloidal mixtures of polystyrene latex (PSL) and negatively charged silica nanoparticles were demonstrated. Porous particles were successfully produced by negatively charged PSL colloids. On the other hand, positively charged PSL colloids tended to generate hollow particles. The measured particle size distribution (PSD) of hollow particles agreed well with the calculated PSD using a mass balance principle of droplet to drying particles of silica and PSL composites. However, for porous particle formation, the measured PSD was smaller than the calculated PSD. The effects of PSL and silica colloids concentrations on a starting material as well as process residence time on the final porous particles were also investigated. A high PSL colloid concentration, low silica colloid concentration, and a short residence time of the process led to higher PSD deviation between the measurement and the calculation. The cause of these phenomena was also discussed in this article.