์•Œ๋ฆผ
๋’ค๋กœ

RESEARCH AREAS


Interface Laboratory
Life is a Journey, not a destination.

Supercritical fluid


  There is no surface tension in a supercritical fluid, as there is no liquid / gas phase boundary. By changing the pressure and temperature of the fluid, the properties can be “tuned” to be more liquid or more gas like. One of the most important properties is the solubility of material in the fluid. Solubility in a supe rcritical fluid tends to increase with density of the fluid. Since density increases with pressure, then solubility also tends to increase with pressure. The relationship with temperature is a little more complicated. At constant density, solubility will increase with temperature. However, close to the critical point, the density can drop sharply with a slight increase in temperature. Therefore, close to the critical temperature, solubility often drops with increasing temperature, then rises again.

Applications 


1. Enhancement of CNTs purification and dispersion using supercritical fluids


  Industrial applications of CNTs are strongly dependent upon homogeneous dispersion in organic or aqueous solvents. Although various dispersion techniques has been developed, critical balance between conductivity and transparency for transparent electrodes has not been achieved yet.

  Especially Single walled carbon nanotube (SWCNT) having excellent physical and chemical properties has wide-ranged applications including transparent conducting films. Dispersion of SWCNT, especially debundling, is crucial for fabricating commercial products which need to get better transparency by reducing a percolation threshold.

  In this study, we use supercritical fluids (SCFs) for enhancing purification and debundling, where SCF is expected to attenuate van der Waals interaction between individual tubes. Near-IR and Raman spectra will be presented for proving debundling. Additionally it will be presented that impurities originated from residual catalysts.

2. Purification of organic nanomaterials by supercritical fluids treatments


  We build a effective purification process of organic nanomaterials using supercritical fluids systems. These technology can replace conventional processes having low yields due to thermal modification, especially for sublimation processes. Specifically we applied supercritical fluids along with organic solvents to the organic nanomaterials and developed purification processes including a re-crystallization in supercritical fluids. In these simple processes residual impurities in the materials can selectively be extracted without chemical damages on them.

Nanoparticles and nanocomposites


 There are many strong point to the nanocomposites. However, industrial applications are still limited because an aggregation between nanofillers in the matrices. For the dispersion, we will present a novel scheme of surface modification on silica nanoparticles with silanes using sonochemical reaction where composition and surface density of silanes can be controlled in order to reduce particle-particle attractive interaction in sophisticated matrix environments

Applications 


1. Surge resistant enameled wires using polymer/silica nanocomposite


- Applications of enameled wire

Enameled wire = magnet wire

- Structure of organic/inorganic nanocomposite coated enameled wire


- Coating shell : Polymer

: Polyvinylformal, Polyester, Polyurethane, Polyesterimide, Polyamideimide, Polyimide, etc.


- Conducting core : Metal

: Copper, Aluminum, Silver, Gold, Tin, Iron, etc.


- Inorganic filler : Oxide

: Silica, Titania, Alumina, Zirconia, Zinc oxide, Iron oxide, Cromium oxide, Clays.

2. A anti-blocking film using polymer/silica nanocomposite


โ‘  Silica filler โ‘ก Matrix resin โ‘ข Base film


1. A heat resistant O-ring using polymer/silica nanocomposite

2. A soft-mold for reflection film using polymer/silica nanocomposite

3. A high refractive index prism sheet using polymer/titania nanocomposite


Quantum dot

by. Sang-Yul Park and Hyo-Sun Kim


  Quantum dots (QD) are very small semiconductor particles, only several nanometers in size. QD has attracted much attention in both basic research and industrial applications because of its outstanding and novel properties related to the quantum confinement effect. Its sharp emission band can be controlled precisely by adjusting its chemical composition and size and its luminescent efficiency is as high as that of inorganic fluorescent materials. Therefore QDs with a high color gamut have been tried as luminophores in LEDs and photoluminescence (PL) film.


  However, the commercial application of QDs is still challenging because their luminescent properties are degraded when they are aggregated and also when exposed to harsh environments such as high energy light, oxidants, moisture, and high temperature. To enhance their dispersion and protection from such environments, the incorporation of QDs in various materials has been extensively studied. Polymeric materials have frequently been chosen as an encapsulation or matrix material because of their flexibility, processibility, and optical transparency.


Graphene oxide

by. Je-seung Yoo


  Graphene oxide (GO) prepared from oxidation of graphite is a chemically exfoliated single layer sheet with the oxygen-containing functional groups (i.e., epoxy, hydroxyl, carbonyl, and carboxyl groups), capable of producing stable and homogeneous colloidal suspensions in various polar solvents and also covalently attaching to various functional molecules and nanoparticles.

  We prepared magnetite-graphene oxide (GO) hybrid through non-covalent pathway assisted by ultrasound. Unlike precipitation and covalent modification, oxygen-containing functional groups on GO have not been consumed during the hybridization. This method keeps the hybrid water solubility and functionality such as heavy metal ion absorption.


Cellulose nanofibrils

by. Sang-Yul Park and Da-Hee Kim  


  Cellulose is the most abundant polysaccharide on earth. It is a highly ordered polymer of cellobiose chains aggregated by numerous strong intermolecular hydrogen bonds between hydroxyl groups of adjacent macromolecules, forming cellulose microfibrils.


  Basically, there are two main families of nanocellulose materials,

(1) Cellulose nanocrystals (CNCs) obtained by acid hydrolysis

(2) Cellulose nanofibrils (CNFs) obtained by mechanical disintegration




  Cellulose paper-based packaging is lightweight, low-cost, and sustainable. CNFs have exceptional optical and mechanical properties. The good oxygen barrier properties of CNFs can be attributed to the dense network formed by nanofibrils with smaller and more uniform dimensions.

The use of CNFs in films, composites, and coatings has found to substantially reduce the oxygen permeability within these materials.

Electrospinning  & spray (CNF)

by. Hyo-Jung Lee


  Electrospinning is a fascinating fiber fabrication technique. When a sufficiently high voltage is applied to a liquid droplet, the body of the liquid becomes charged, and electrostatic repulsion counteracts the surface tension and the droplet is stretched. Eventually, the charge repulsion overcomes the surface tension, causing the initiation of a jet. As this jet travels, the solvent evaporates and an appropriate collector can be used to capture the polymer fiber.


  

  Electrospinning provides a possibility to produce nanofibers with different structures and morphologies by varying the processing parameters.

Membrane

by. Hyo-Jung Lee


[...]

Nano-bio materials

by. Hyo-Jung Lee


[...]

Interface Laboratory

Life is a Journey, not a destination

Get the latest news and various benefits here. 

Enter

Tel. 070-7539-9093  |  Address : ์„œ์šธ์‹œ ๊ด‘์ง„๊ตฌ ๋Šฅ๋™๋กœ 209 ์„ธ์ข…๋Œ€ํ•™๊ต ์œจ๊ณก๊ด€ 607ํ˜ธ

Professor : Young-Soo Seo

 - Department of Nano technology and advanced materials engineering -

Copyright โ“’ interface lab Since 2006