Shin-Hyun Kim

Chameleons use a non-close-packed array of guanine nanocrystals in iridophores to develop and tune skin colors in the full visible range. Inspired by the biological process uncovered in panther chameleons, we designed photonic films containing a non-close-packed face-centered-cubic array of silica particles embedded in an elastomer. The non-close-packed array is formed by interparticle repulsion exerted by solvation layers on the particle surface, which is rapidly captured in the elastomer by ph

High Resolution Image Download MS PowerPoint Slide Self-assembly of monodisperse colloidal particles into regular lattices has provided relatively simple and economical methods to prepare photonic crystals. The photonic stop band of colloidal crystals appears as opalescent structural colors, which are potentially useful for display devices, colorimetric sensors, and optical filters. However, colloidal crystals have low durability, and an undesired scattering of light makes the structures white a

Janus-Mikrokügelchen mit einer superhydrophoben und einer hydrophilen Oberflächenhälfte wurden auf photochemischem Weg aus Pickering-Emulsionströpfchen erhalten. An einer Luft-Wasser-Grenzfläche bilden diese Kügelchen eine undurchdringliche und flexible superhydrophobe Barriere. Potenzielle Anwendungen finden sich in größenabhängigen semipermeablen Membranen, schwimmenden Mikromaschinen und superhydrophoben Beschichtungen.

We introduce an emulsification technique that creates monodisperse double-emulsion drops with a core-shell geometry having an ultra-thin wall as a middle layer. We create a biphasic flow in a microfluidic capillary device by forming a sheath flow consisting of a thin layer of a fluid with high affinity to the capillary wall flowing along the inner wall of the capillary, surrounding the innermost fluid. This creates double-emulsion drops, using a single-step emulsification, having a very thin flu

Recent advances in microfluidics have enabled the controlled production of multiple-emulsion drops with onion-like topology. The multiple-emulsion drops possess an intrinsic core-shell geometry, which makes them useful as templates to create microcapsules with a solid membrane. High flexibility in the selection of materials and hierarchical order, achieved by microfluidic technologies, has provided versatility in the membrane properties and microcapsule functions. The microcapsules are now desig

Long-term storage and controlled release of multiple components while avoiding cross-contamination have potentially important applications for pharmaceuticals and cosmetics. Polymersomes are very promising delivery vehicles but cannot be used to encapsulate multiple independent components and release them in a controlled manner. Here, we report a microfluidic approach to produce multiple polymersomes, or polymersomes-in-polymersome by design, enabling encapsulation and programmed release of mult

Isotropic microparticles prepared from a suspension that undergoes polymerization have long been used for a variety of applications. Bulk emulsification procedures produce polydisperse emulsion droplets that are transformed into spherical microparticles through chemical or physical consolidation. Recent advances in droplet microfluidics have enabled the production of monodisperse emulsions that yield highly uniform microparticles, albeit only on a drop-by-drop basis. In addition, microfluidic de

Electroresponsive photonic Janus balls with optical and electrical anisotropy were prepared using a high-throughput optofluidic device, which produced monodisperse emulsion drops. Self-organized colloidal crystals in emulsion droplets displayed isotropic structural colors in their own respective domains. Electrical anisotropy induced by the presence of carbon black enabled alignment of the balls under the AC electric field.

Monodisperse aqueous emulsion droplets encapsulating colloidal particles were produced in the oil phase, and controlled microwave irradiation of the aqueous drop phase created spherical colloidal crystals by so-called evaporation-induced self-organization of the colloidal particles. Unlike usual colloidal crystals, colloidal crystals in spherical symmetry (or photonic balls) possessed photonic band gaps for the normal incident light independent of the position all over the spherical surface. Whi

Various structural motifs of colloidal crystals are prepared by UV-induced consolidation over fast time scales. Our strategy with a high-throughput optofluidic technique allows unprecedented control over the 3D organization of the colloids, as well as the combination of different materials over multiple length scales, thus expanding the potential for specific applications such as e-papers and light emission modulators.

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 w

Janus microspheres composed of superhydrophobic and hydrophilic hemispherical surfaces were prepared using photocurable Pickering emulsion droplets. Upon placement at an air–water interface, an impregnable superhydrophobic barrier with high flexibility is formed. These microspheres have great potential in size-dependent semipermeable membranes, floating micromachines, and superhydrophobic coatings.

Polymeric onions: A facile method to produce monodisperse multiple emulsion drops of high order is developed using a capillary microfluidic device. Coaxial multiphase flows are stabilized by confinement in microcapillary and emulsified to multiple emulsion drops. The breakup of coaxial interfaces, triggered by the core-drop, facilitates the making of multiple emulsion drops of onionlike configuration. Detailed facts of importance to specialist readers are published as ”Supporting Information”. S