Youngjune Kang

We report a general approach toward dispersing single-walled carbon nanotubes (SWNTs) in solvents and polymer materials, by encapsulating SWNTs within cross-linked micelles. Micelles made from polystyrene-block-poly(acrylic acid) (PS-b-PAA), an amphiphilic block copolymer, are first assembled around SWNTs by gradually adding H2O to a suspension of nanotubes in dimethylformamide. The hydrophilic, outer shells of these micelles are then chemically cross-linked with a difunctional linker molecule.

Plated gold: Self-assembly of core/shell nanostructures occurs spontaneously when gold nanoparticles are combined with amphiphilic block copolymers. Polymer cross-linking then topologically fixes the composite nanostructure (see picture). The thickness of the polymer shell, as well as the optical and chemical properties of the composite nanostructure, are precisely determined by the molecular characteristics of the assembled block copolymer.

Quasi-amorphous colloidal structures exhibiting angle-independent tunable photonic colors in response to the electric stimuli. Moderately polydisperse colloidal Fe3O4@SiO2 nanoparticles dispersed in organic solvents exclusively form quasi-amorphous photonic materials at sufficiently high concentrations, and which reversibly reflect incident light in visible region in response to the relatively low bias voltages.

When Au nanoparticles are encapsulated within shells of cross-linked, block copolymer amphiphiles, the structure of the shells is determined by the initial interaction between the amphiphile and the nanoparticle surface. In the case of small nanoparticles, for which particle size is comparable to the dimension of the block copolymer (ρ Au / R g ≈ 1), particles act like solutes that are dissolved within polystyrene- block -poly(acrylic acid) (PS- b -PAA) micelle cores. In the case of larger nanop

Colloidal perovskite nanocrystals based on formamidinium lead halide (FAPbX 3 ) have been synthesized by the ligand-assisted reprecipitation method using PbX 2 –dimethyl sulfoxide complexes as precursors at room temperature. Well-defined cubic-shaped FAPbX 3 nanocrystals have been obtained with a size d of ∼10 nm. The synthesized FAPbX 3 nanocrystals show bright photoluminescence with a high photoluminescence quantum yield (75% for FAPbBr 3 ). The lifetimes of FAPbBr 3 nanocrystals were measured

Au nanoparticles encapsulated within polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles assemble into regular, one-dimensional arrays when they are exposed to solvent conditions that relax interfacial curvature in the micellar shell. Nanoparticle chaining was induced by adding salt, acid, or cationic carbodiimide to the suspension of purified encapsulated Au nanoparticles (Au@PS-b-PAA). The resulting assemblies were characterized by scanning and transmission electron microscopies, by dark-

We report a facile way of fabricating hybrid organic/inorganic photonic gels by selective swelling and subsequent infiltration of SiO(2) into one type of lamellar microdomain previously self-assembled from modest-molecular-weight block copolymers. Transparent, in-plane lamellar films were first prepared by assembly of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP), and subsequently the P2VP domains were swollen with a selective solvent, methanol. The swollen structures were then fixated by

Plastic pixels: Electrically tunable photonic pixels exhibiting nonvolatile photonic colors are demonstrated by coupling the hysteretic optical properties of PS-b-P2VP block copolymer photonic gels with an electrochemically induced pH gradient. The optical volatility of photonic pixels was tuned by controlling the hysteresis strength and the conversion pH value, which were both highly dependent on the species of anions pairing with pyridinium groups. Detailed facts of importance to specialist re

Beschichtetes Gold: Kern/Schale-Nanostrukturen entstehen spontan, wenn Goldnanopartikel mit amphiphilen Blockcopolymeren kombiniert werden. Die Polymervernetzung fixiert dann die Nanostruktur topologisch (siehe Bild). Die Dicke der Polymerschale sowie die optischen und chemischen Eigenschaften der gesamten Nanostruktur werden durch die molekularen Merkmale der verwendeten Blockcopolymere exakt festgelegt. Supporting information for this article is available on the WWW under http://www.wiley-vch.

Efficiency roll-off is a significant issue in blue light-emitting diodes (LEDs), but its origin still remains controversial.

Abstract In spite of efforts to fabricate stimuli‐sensitive structural colors (SCs) of self‐assembled block copolymer (BCP) photonic crystals (PCs) with potential applications in displays, media boards, and sensors, few studies have demonstrated BCP PCs suitable for high‐density nonvolatile information storage. Herein, a simple but robust route for multilevel nonvolatile information recording using a BCP PC is presented. The proposed method is based on the spatially controlled crosslinking of mi

Abstract Physical entities with inherent randomness have been investigated as anti‐counterfeiting labels based on physical unclonable functions (PUFs). Herein, a transparent and flexible optical PUF label associated with multilevel complexity is demonstrated by taking advantage of the optical properties of hierarchical morphologies of the composite film composed of metal halide perovskite nanoparticles (MAPbBr 3 NPs) and the intrinsic spinodal‐decomposition‐like phase separation of polymer blend