Abstract
Double emulsions are complex fluid systems, in which droplets of a dispersed liquid phase contain even smaller dispersed liquid droplets. Particularly, water-in-oil-in-water double emulsions provide significant advantages over simple oil-in-water emulsions for microencapsulation, such as carrier of both aqueous and oily payloads and sustained release profile. However, double emulsions are thermodynamically unstable systems consisting typically of relatively large droplets. Here we show that nanoscale water-in-oil-in-water double emulsions can be prepared by adding a silica precursor polymer, hyperbranched polyethoxysiloxane, to the oil phase without any additional surfactants. The resulting double miniemulsions are transformed to robust water@SiO2@polymer@SiO2 nanocapsules via conversion of the precursor to silica and polymerization of the oil phase. Other intriguing nanostructures like nanorattles and Janus-like nanomushrooms can also be obtained by changing preparation conditions. This simple surfactant-free double miniemulsion polymerization technique opens a promising avenue for mass production of various complex hybrid nanostructures that are amenable to numerous applications.
Highlights
Double emulsions are complex fluid systems, in which droplets of a dispersed liquid phase contain even smaller dispersed liquid droplets
Water-in-oil-in-water (W/O/W)-type double emulsions where each dispersed water droplet is separated from the continuous aqueous phase by a layer of an oil phase can provide significant advantages over simple oil-in-water (O/W) emulsions for microencapsulation applications, such as carrier of both aqueous and oily payloads and sustained release profile[4,5,6,7,8]
Nanoscale double emulsions that were stable for months were prepared using amphiphilic diblock copolypeptides, in which the control of hydrogen bond presentation in polypeptide segments acts as a stabilizing factor, though the reduction of droplet size succeeded by passage six times through a microfluidic homogenizer[12]
Summary
Double emulsions are complex fluid systems, in which droplets of a dispersed liquid phase contain even smaller dispersed liquid droplets. We show that nanoscale water-in-oil-in-water double emulsions can be prepared by adding a silica precursor polymer, hyperbranched polyethoxysiloxane, to the oil phase without any additional surfactants. The resulting double miniemulsions are transformed to robust water@SiO2@polymer@SiO2 nanocapsules via conversion of the precursor to silica and polymerization of the oil phase. Other intriguing nanostructures like nanorattles and Janus-like nanomushrooms can be obtained by changing preparation conditions This simple surfactant-free double miniemulsion polymerization technique opens a promising avenue for mass production of various complex hybrid nanostructures that are amenable to numerous applications. Double emulsions are thermodynamically unstable systems consisting typically of relatively large droplets They are usually prepared using a two-step emulsification process involving the formation of a primary water-in-oil (W/O) emulsion under highshear conditions and the subsequent dispersion of this W/O emulsion into water with a relatively gentle shear force to avoid rupture of the internal water droplets, while a one-step procedure often leads to badly reproducible results[3]. Other intriguing nanostructures like nanorattles and Janus-like nanomushrooms can be prepared under certain conditions
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