Publications by authors named "Jeseung Yoo"

Polymer-like dielectrics with superb thermal conductivity as well as high dielectric properties hold great promise for the modern electronic field. Nevertheless, integrating these properties into a single material simultaneously remains problematic due to their mutually limited physical connotations. In this study, we developed high-quality thermally conductive epoxy composites with excellent dielectric properties.

View Article and Find Full Text PDF

The protection of skin cells against intense ultra-violet (UV) rays is of greater concern and needs immediate attention. Sustainable efforts and strategies are in progress to minimize the factors that adversely affect skin cells. Herein, we synthesized zinc oxide (ZnO) in the form of core-shell (Core@Shell) or reverse core-shell (RCore@Shell) structure where silica was synthesized as a shell or core, respectively on the surface of cellulose nanofiber (CNF).

View Article and Find Full Text PDF

Transition metal oxides used as electrode materials for flexible supercapacitors have attracted huge attention due to their high specific capacitance and surface-to-volume ratio, specifically for cobalt oxide (CoO) nanoparticles. However, the low intrinsic electronic conductivity and aggregation of CoO nanoparticles restrict their electrochemical performance and prevent these electrode materials from being commercialized. Herein, a facile, advantageous, and cost effective sol-gel synthetic route for growing CoO nanoparticles uniformly over a low cost and eco-friendly one-dimensional (1D) hydrophilic cellulose nanofiber (CNF) surface has been reported.

View Article and Find Full Text PDF

We fabricated a magnetite nanoparticle-graphene oxide (GO) hybrid via a non-chemical and one-step process assisted by ultrasound in an aqueous solution where the nanoparticle attached to the hydrophobic region on graphite oxide (multi-layered GO) which, at the same time, was exfoliated. Unlike chemical methods such as precipitation, oxygen-containing functional groups on GO have not been consumed or reduced during the hybridization, leading that this hybrid exhibited good water solubility and high adsorption capacity for heavy metal ions such as Pb(II) and Au(III). After the adsorption, the hybrid was instantly collected using a magnet.

View Article and Find Full Text PDF

We present a simple and facile approach to creating asymmetrically modified graphene oxide sheets by grafting polymers with different polarities. Single-layered Janus graphene derivatives were prepared by grafting polymers with different polarities at the liquid-gas interface through one step functionalization. This approach allows obtaining free-standing monolayers of Janus graphene oxide sheets for large area, and also controlling the morphology (i.

View Article and Find Full Text PDF

We investigate the effect of adding graphene oxide (GO) sheets at the polymer-polymer interface on the dewetting dynamics and compatibility of immiscible polymer bilayer films. GO monolayers are deposited at the poly(methyl methacrylate) (PMMA)-polystyrene (PS) interface by the Langmuir-Schaefer technique. GO monolayers are found to significantly inhibit the dewetting behavior of both PMMA films (on PS substrates) and PS films (on PMMA substrates).

View Article and Find Full Text PDF

We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ∼12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.

View Article and Find Full Text PDF

Competitive adsorption isotherms of Cu(II), Pb(II), and Cd(II) were examined on a magnetic graphene oxide (GO), multiwalled carbon nanotubes (MWCNTs), and powered activated carbon (PAC). A series of analyses confirmed the successful synthesis of the magnetic GO based on a simple ultrasonification method. Irrespective of the adsorbents, the adsorption was highly dependent on pH, and the adsorption was well described by the Langmuir isotherm model.

View Article and Find Full Text PDF

Enhancement of the production yield of boron nitride nanotubes (BNNTs) with high purity was achieved using an amorphous boron-based precursor and a nozzle-type reactor. Use of a mixture of amorphous boron and Fe decreases the milling time for the preparation of the precursor for BNNTs synthesis, as well as the Fe impurity contained in the B/Fe interdiffused precursor nanoparticles by using a simple purification process. We also explored a nozzle-type reactor that increased the production yield of BNNTs compared to a conventional flow-through reactor.

View Article and Find Full Text PDF
Article Synopsis
  • The study demonstrates using octadecylamine (ODA) surfactant as a template to control the assembly of graphene oxide (GO) sheets at the liquid-gas interface, which is important for graphene device applications.
  • By applying Langmuir-Schaefer or Langmuir-Blodgett techniques, researchers created densely packed 2D GO films on various substrates, and ODA molecules helped maintain their morphology during compression by causing wrinkling instead of overlapping.
  • The resulting wrinkled graphene structures remained stable even after treatments aimed at enhancing their properties, indicating potential use in nanoelectronics, supercapacitors, and fuel cells.
View Article and Find Full Text PDF