title: 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.
authors.affiliation: School of Engineering and Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts, USA.
authors.forename: Shin-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Alireza
authors.initials: A
authors.lastname: Abbaspourrad
authors.forename: David A
authors.initials: DA
authors.lastname: Weitz