Microdroplet Of Suspension Research Articles

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

.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.

Interaction of optical Whispering Gallery Modes with the surface layer of evaporating droplet of suspension

We investigate scattering of light on micro droplets of suspensions of 100-nm and 225-nm-radius dielectric spheres in glycols. Rapid increase of scattered light intensities accompanied by light depolarisation was observed on presumed formation of the surface layer of inclusions. We determined the effective refractive index of the droplet (surface) evolving during the formation of the surface layer of inclusions. We present a model enabling identification of interaction of surface structures of inclusions with Whispering Gallery Modes of the droplet. It seems possible to exploit the evaporation of micro droplets of suspension as a method of production of composite objects with very specific indices of refraction.