Gi Ra Lee

Synthesis and self-assembly of structured colloids is a nascent field. Recent advances in this area include the development of a variety of practical routes to produce robust photonic band-gap materials, colloidal lithography for nanopatterns, and hierarchically structured porous materials with high surface-to-volume ratios for catalyst supports. To improve their properties, non-conventional suprastructures have been proposed, which could be built up using binary or bimodal mixtures of spherical

'Patchy colloids' is a term that has been recently introduced to indicate specially engineered particles with directional interactions. Based on this concept, a 'bottom-up' process for fabricating functional materials and devices has been envisioned, which employs colloidal building blocks and mimics molecular bonding. This article reviews recent progress which has been made in the synthesis and self-assembly of patchy colloids and discusses future directions as well as unresolved challenges.

This article investigates the role of shape in colloidal self-assembly and argues for the importance of a tight synergy between particle design and assembly strategies. To this end, we review synthetic methodologies developed to impart colloidal building blocks with anisotropic shapes and self-assembly mechanisms that exploit geometry to direct and control the particles' organization. This paper, which deliberately focuses on micron-scale colloids, is divided into two main sections. Firstly, we

Block copolymers confined in emulsion droplets self-organize into polymeric particles, and cooperative self-assembly driven by deformable interfacial properties produces unprecedented structural motifs such as prolates of stacked lamellae, oblates with biomimetic nanoscale architecture, and spheres with tori or helices (see figure). Interface-mediated structural evolution provides a novel route for synthesizing functional particles with unique nanostructures.

We demonstrate continuous roll-to-roll production of highly conductive silver network films on a plastic substrate via mechanical and chemical welding processes. This process included three essential steps: (i) solvent spraying, (ii) roll compression, and (iii) salt treatment and washing. The sheet resistance of the resulting AgNW film was 5 Ω sq(-1) at 92% transmittance, which was the lowest sheet resistance and the highest transparency among the values reported previously for solution-processe

An emulsion encapsulation and shrinkage technique for producing large quantities of colloidally stable clusters of microspheres (see Figure) is demonstrated. In spite of differences in particle properties and interactions, the sequence of cluster packings remains the same for three different systems, suggesting that the sphere-packing process can be successfully applied to a wide range of colloidal materials.

Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even

A microfluidic device is used to generate uniform emulsion droplets containing monodisperse latex spheres at specific intervals by shearing off the tip of the incoming aqueous phase at the junction of two microfluidic channels (see Figure). The water‐in‐oil emulsions are converted to uniform colloidal assemblies of latex spheres by slowly removing water from the aqueous emulsion droplets.

Surface carbon coating to improve the inherent poor electrical conductivity of lithium iron phosphate (LiFePO4, LFP) has been considered as most efficient strategy. Here, we also report one of the conventional methods for LFP but exhibiting a specific capacity beyond the theoretical value, ultrahigh rate performance, and excellent long-term cyclability: the specific capacity is 171.9 mAh/g (70 μm-thick electrode with ∼10 mg/cm(2) loading mass) at 0.1 C (17 mA/g) and retains 143.7 mAh/g at 10 C (

Uniform spherical colloidal assemblies of closely packed monodisperse colloidal particles have been prepared by injecting an aqueous suspension of polymer spheres into a surfactant-laden oil phase through a micropipette. The size of these assemblies can be controlled by varying the injection pressure or particle concentration. The Figure shows 6.3 μm diameter assemblies composed of 230 nm particles.

We report a remarkably rapid method for assembling pristine graphene platelets into a large area transparent film at a liquid surface. Some 2-3 layer pristine graphene platelets temporally solvated with N-methyl-2-pyrrolidone (NMP) are assembled at the surface of a dilute aqueous suspension using an evaporation-driven Rayleigh-Taylor instability and then are driven together by Marangoni forces. The platelets are fixed through physical binding of their edges. Typically, 8-cm-diameter circular gra

Ordered macroporous particles of silica and titania were fabricated by colloidal templating. The colloidal templates were assembled through colloidal crystallization of suspended polystyrene latex sphere particles in aqueous droplets straddling an air−oil interface. The procedures involve first preparing spherical colloidal crystalline particles of polystyrene latex spheres and then infusing them with metal precursor solutions that form silica or titania in the interstices. Finally, calcination

Submicron emulsions could be produced via the tip-streaming process in a flow-focusing microfluidic device. In this article, the stability of the liquid cone and thread for tip-streaming mode could be significantly improved by employing a three-dimensional flow-focusing device, in which the hydraulic resistance was adjusted by modulating the channel heights in the flow focusing area, orifice, downstream and dispersed phase inlet channel. The pressure range for tip-streaming mode was enlarged sig