Sodium dodecyl sulfate microaggregates with diversely developed surfaces: Formation from free microdroplets of colloidal suspension

摘要

.Unsupported drying of microdroplets of colloidal suspension can lead to the formation of complex micro-morphologies with quasi-spherical symmetry. Herein, drying of levitating microdroplets of suspension of SiO2 nanospheres in diethylene glycol (DEG) with sodium dodecyl sulfate (SDS) is reported as a method for producing such microstructures with diversely developed surfaces. Dried products are soft-landed on a substrate and studied with scanning electron microscopy (SEM). The smallest SDS/SiO2 composites with the surface formed of crystallised SDS and interior filled with SiO2 nanospheres preserve the spherical symmetry. Larger microdroplets with higher initial mass fractions of SDS dry up to developed microstructures with SiO2 nanospheres arranged in-between the crystallised SDS flakes which are similar to curved lobe cabbage leaves or desert rose-like structures with radially directed SDS crystals. Largest microdroplets with highest initial mass fractions of SDS formed doughnut-shaped micro-containers filled with aggregated SiO2 nanospheres. In all these, SiO2 nanospheres served as a frame for the SDS crystallisation.