Hanyang University · Engineering
Professor Youngjong Kang's research lab specializes in the design and fabrication of advanced functional nanomaterials, with a focus on block copolymer-based nanostructures, carbon nanotube dispersion, and stimuli-responsive photonic materials. The lab develops innovative strategies for the self-assembly and stabilization of nanoparticles—such as gold and single-walled carbon nanotubes—within cross-linked micellar or polymeric matrices, enabling precise control over morphology, optical properties, and interfacial engineering. A key research direction involves creating electrically tunable photonic materials and smart pixels with nonvolatile color switching, leveraging the unique responsiveness of block copolymer gels to external stimuli like voltage and pH. The lab also explores the hierarchical organization of nanoparticles into ordered superstructures through controlled interfacial engineering and environmental triggers.
Figures are computed from collected data and may differ slightly.
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.
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.
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 (ρAu/Rg ≈ 1), particles act like solutes that are dissolved within polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelle cores. In the case of larger nanoparticles
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-
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
Highly conductive and stretchable electromagnetic interference shielding (EMI) materials were developed using a silver nanoparticle/elastomeric polymer (NP/SBS) composite.
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<sub>3</sub> NPs) and the intrinsic spinodal-decomposition-like phase separation of polymer blen
Abstract An additive, 1,4‐butadiene sulfone (BDS), which generates H 2 SO 3 by in situ thermal retro‐Diels‐Alder decompositions, is used for preparing high β‐phase polyvinylidene fluoride (PVDF) films. Because of preferential multiple non‐covalent interactions of H 2 SO 3 with all‐trans configuration of PVDF, β‐phase PVDF is spontaneously induced without mechanical drawing and/or extensive thermal annealing process. PVDF films cast from PVDF/BDS/water solutions exhibit high β‐phase content ( f β
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