Jinhan Cho

Abstract The effective implantation of conductive and charge storage materials into flexible frames has been strongly demanded for the development of flexible supercapacitors. Here, we introduce metallic cellulose paper-based supercapacitor electrodes with excellent energy storage performance by minimizing the contact resistance between neighboring metal and/or metal oxide nanoparticles using an assembly approach, called ligand-mediated layer-by-layer assembly. This approach can convert the insu

We introduce a novel and versatile approach for preparing self-assembled nanoporous multilayered films with tunable optical properties. Protonated polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and anionic polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles (BCM) were used as building blocks for the layer-by-layer assembly of BCM multilayer films. BCM film growth is governed by electrostatic and hydrogen-bonding interactions between the opposite BCMs. Both film porosity

Abstract Electrical communication between an enzyme and an electrode is one of the most important factors in determining the performance of biofuel cells. Here, we introduce a glucose oxidase-coated metallic cotton fiber-based hybrid biofuel cell with efficient electrical communication between the anodic enzyme and the conductive support. Gold nanoparticles are layer-by-layer assembled with small organic linkers onto cotton fibers to form metallic cotton fibers with extremely high conductivity (

We examine the interactions between gold nanoparticles stabilized by the 4-(dimethylamino)pyridine (DMAP−Au NP ) and various polyelectrolytes (PEs), both in solution and in layer-by-layer (LbL) assembled multilayer films. UV−vis spectrophotometry studies showed that the plasmon absorption band of the DMAP−Au NP in solution red-shifts and broadens in the presence of poly(sodium 4-styrenesulfonate) (PSS), poly(allylamine hydrochloride) (PAH), or poly(ethyleneimine) (PEI). This suggests that the po

Polyelectrolyte multilayer thin films were prepared via the alternate deposition of poly(allylamine hydrochloride) (PAH) and a blend of poly(acrylic acid) (PAA) and poly(styrenesulfonate) (PSS). When the pH of the blend solution was 3.5, the presence of PAA in this solution significantly increased the total film thickness. With only 10 wt % PAA in the blend adsorption solution, a large increase in film thickness was observed (92 nm cf. 18 nm). It was also demonstrated that the total amount of PS

Electrochemical properties of redox proteins, which can cause the reversible changes in the resistance according to their redox reactions in solution, are of the fundamental and practical importance in bioelectrochemical applications. These redox properties often depend on the chemical activity of transition metal ions as cofactors within the active sites of proteins. Here, we demonstrate for the first time that the reversible resistance changes in dried protein films based on ferritin nanoparti

Hydrogels have diverse chemical properties and can exhibit reversibly large mechanical deformations in response to external stimuli; these characteristics suggest that hydrogels are promising materials for soft robots. However, reported actuators based on hydrogels generally suffer from slow response speed and/or poor controllability due to intrinsic material limitations and electrode fabrication technologies. Here, we report a hydrogel actuator that operates at low voltages (<3 volts) with h

Abstract For the development of wearable electronics, the replacement of rigid, metallic components with fully elastomeric materials is crucial. However, current elastomeric electrodes suffer from low electrical conductivity and poor electrical stability. Herein, a metal‐like conductive elastomer with exceptional electrical performance and stability is presented, which is used to fabricate fully elastomeric electronics. The key feature of this material is its wrinkled structure, which is induced

Deconstructible polymeric films have potential applications in the areas of drug delivery, patterning, and membrane science. Here, we report on the preparation of heterogeneous multilayer films comprising alternate stacks of hydrogen-bonded (poly(4-vinylpyridine) (P4VP) and poly(acrylic acid, sodium salt) (PAA)) and electrostatically formed (poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH)) layers via the layer-by-layer (LbL) assembly technique. We demonstrate that

A robust method for preparing nanocomposite multilayers was developed to facilitate the assembly of well-defined hydrophobic nanoparticles (i.e., metal and transition metal oxide NPs) with a wide range of functionalities. The resulting multilayers were stable in both organic and aqueous media and were characterized by a high NP packing density. For example, inorganic NPs (including Ag, Au, Pd, Fe₃O₄, MnO₂) dispersed in organic media [corrected]were shown to undergo layer-by-layer assembly with a

We introduce an innovative and robust method for the preparation of nanocomposite multilayers, which allows accurate control over the placement of functional groups as well as the composition and dimensions of individual layers/internal structure. By employing the photocross-linkable polystyrene (PS-N(3), M(n) = 28.0 kg/mol) with 10 wt % azide groups (-N(3)) for host polymer and/or the PS-N(3)-SH (M(n) = 6.5 kg/mol) with azide and thiol (-SH) groups for capping ligands of inorganic nanoparticles

We present multifunctional dendrimer ligands that serve as the charge injection controlling layer as well as the adhesive layer at the interfaces between quantum dots (QDs) and the electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs). Specifically, we use primary amine-functionalized dendrimer ligands (e.g., a series of poly(amidoamine) dendrimers (PADs, also referred to PAMAM)) that bind to the surface of QDs by replacing the native ligands (oleic acids) and also to the s