Amphiphilic Crescent-Moon-Shaped Microparticles Formed by Selective Adsorption of Colloids

Abstract

We use a microfluidic device to prepare monodisperse amphiphilic particles in the shape of a crescent-moon and use these particles to stabilize oil droplets in water. The microfluidic device is comprised of a tapered capillary in a theta (θ) shape that injects two oil phases into water in a single receiving capillary. One oil is a fluorocarbon, while the second is a photocurable monomer, which partially wets the first oil drop; silica colloids in the monomer migrate and adsorb to the interface with water but do not protrude into the oil interface. Upon UV-induced polymerization, solid particles with the shape of a crescent moon are formed; removal of fluorocarbon oil yields amphiphilic particles due to the selective adsorption of silica colloids. The resultant amphiphilic microparticles can be used to stabilize oil drops in a mixture of water and ethanol; if they are packed to sufficient surface density on the interface of the oil drop, they become immobilized, preventing direct contact between neighboring drops, thereby providing the stability.

Osmotic-pressure-controlled concentration of colloidal particles in thin-shelled capsules

“…The agreement with the model also shows that other effects, such as the Laplace pressure of the capsule, do not significantly affect the transport. This is expected, since even at long times, when the radius of drop approaches R 0 (C 0 /C out ) 1/3 , the Laplace pressure of the capsuleswhich is equal to 4g/R, where g is the interfacial tension between water and ETPTA (B2.24 mNm À 1 ) 22 -is two orders of magnitude less than the osmotic pressure 23 .…”

Enhanced-throughput production of polymersomes using a parallelized capillary microfluidic device

“…For example, single-emulsion drops, prepared in such microfluidic devices, can be employed to make monodisperse spherical microparticles with optical, electrical, and magnetic functionalities (Kim et al 2008a(Kim et al , 2010Nie et al 2006;Nisisako et al 2006;Zhao et al 2008). In addition, nonspherical microparticles can also be prepared by deforming the drops or making pairs of drops (Dendukuri et al 2005;Hwang et al 2008;Kim et al 2011a;Nisisako and Torii 2007;Xu et al 2005). Moreover, microfluidic emulsification enables generation of doubleemulsion drops, or drops in drops, in an efficient way, which is otherwise difficult to achieve using bulk emulsification (Okushima et al 2004;Utada et al 2005).…”

Controllable Microfluidic Fabrication of Microstructured Materials from Nonspherical Particles to Helices

“…[23,24] With excellent manipulation of microflows, [28][29][30] microfluidic technique provides a powerful platform for fabricating nonspherical microparticles with versatile structures and compositions. [26,31,32] Mask-assisted selective polymerization of photo-curable solution in microchannel can fabricate nonspherical microparticles with flexible shapes depending on their mask, [25,33] and the flow configuration. [34,35] Alternatively, monodisperse emulsion droplets from microfluidics, with versatile shapes, provide excellent templates for engineering uniform nonspherical microparticles.…”

“…[34,35] Alternatively, monodisperse emulsion droplets from microfluidics, with versatile shapes, provide excellent templates for engineering uniform nonspherical microparticles. Deformed droplets confined by microchannel with different dimensions, [26,27] Janus droplets with one curable hemisphere, [31,36] and evolved acorn-shaped droplets from double emulsions, [32] can be generated from microfluidics for fabricating nonspherical microparticles with different shapes. However, for the above-mentioned methods, it is difficult to produce microstructured materials with complex…”