Self-assembled Shells Composed of Colloidal Particles: Fabrication and Characterization
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--Overview-- Precisely controlled containment and release of chemicals is a critical aspect of many important industries and scientific areas including the pharmaceutical, biomedical, and food industries. One convenient way to both capture and release species of interest is by using self-assembled colloidal particles to form a shell around the material. This study explores the morphology and mechanical properties of self-assembled particle coatings around both aqueous and organic materials.
--Experimental-- The authors created two types of emulsions - water in oil (w/o) and oil in water (o/w). Colloidal polystyrene (PS) and divinyl-benzene (DVB) were added to different emulsions and mixed via. The colloidal particles spontaneously migrated to the droplet/continuous phase interface and self-assembled into highly ordered structures. In all cases, no thermal desorption from the droplet surface was observed. After assembly, the particulate shell was stabilized by way of solidification, and sintered. Morphology was analyzed via scanning electron microscopy and optical microscopy. Mechanical tests were performed using calibrated microcantilevers.
--Results-- Different solvents and stabilization methods led to different surface morphologies: