Supraparticle formation from binary mixtures of nanosuspensions via superheated steam drying

In this study, the effect of binary mixtures of colloidal nanosilica suspensions on the supraparticle formation in superheated steam drying at 300 °C is investigated. It is shown that the single droplet drying kinetics and the final supraparticle morphology can be modified by the addition of smaller nanoparticles into a suspension of larger nanoparticles. It was found that the presence of smaller nanoparticles slows down the evaporation of single droplets, delays crust formation, and produces smaller supraparticles. Comparison of the average supraparticle porosity of the bidisperse structures with the porosity data of corresponding monodisperse systems shows a general decrease in porosity. Analysis of the SEM images reveals that at a volume mixing ratio of 25 vol% of small nanoparticles, stable supraparticles are obtained for all initial solids concentration, and at high initial solids concentrations (30 wt%) stable supraparticle were formed at all mixing ratios.