• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.24 no.1
• /
• pp.33-40
• /
• 2014

Poly vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) membrane were prepared by the electrospinning technique. We had applied a DLC coating process and then the surface of the membrane and the contact angle change was investigated. Electrospun fibrous PVdF-HFP membrane surface became to wrinkled shape by Ar plasma treatment and treatment conditions. The wrinkled surface of PVdF-HFP membrane became super-hydrophilic. However, after DLC coating process, it became super-hydrophobic. The resulting surfaces were characterized by water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM). Resultantly it was recognized that the wettability characteristics of the membrane surfaces depended on the chemical composition and surface morphology.

• Macromolecular Research
• /
• v.17 no.7
• /
• pp.533-537
• /
• 2009

This paper introduces a modified electro spinning system for biomedical wound-healing applications. The conventional electrospinning process requires a grounded electrode on which highly charged electro spun ultrafine fibers are deposited. Biomedical wound-healing membranes, however, require a very low charge and a low level of remnant solvent on the electrospun membrane, which the conventional process cannot provide. An electrohydrodynamic process complemented with field-controllable electrodes (an auxiliary electrode and guiding electrodes) and an air blowing system was used to produce a membrane, with a considerably reduced charge and low remnant solvent concentration compared to one fabricated using the conventional method. The membrane had a small average pore size (102 nm) and high porosity (85.1%) for prevention of bacterial contamination. In vivo tests on rats showed that these directly electro spun fibrous membranes produced using the modified electro spinning process supported the good healing of skin bums.

• Journal of Electrochemical Science and Technology
• /
• v.6 no.1
• /
• pp.26-33
• /
• 2015

In this study, cell performance and thermal stability of lithium-ion cells with a polyimide (PI) separator are investigated. In comparison to conventional polyethylene (PE) separator, the PI separator exhibits distinct advantage in microporous structure, leading to superior reliability of the cell. The cells with PI separator exhibit good cell performances as same as the cells with PE separator, but their reliability was superior to the cell with PE separator. Especially in the hot-box test at 150 and 180℃, PI separator showed a contraction percentage close to 0% at 150℃, while the PE separator showed a contraction percentage greater than 10% in both width and length. Therefore, the PI separator can be the promising candidate for separators of the next generation of lithium-ion battery.

• Macromolecular Research
• /
• v.16 no.3
• /
• pp.204-211
• /
• 2008

A platinum-catalyzed polyelectrolyte porous membrane was prepared by solid-state compression of electrospun polystyrene (PS) fibers and in-situ metallization of counter-balanced ionic metal sources on the polymer surface. Using this ion-exchange metal-polymer composite system, fiber entangled pores were formed in the interstitial space of the fibers, which were surrounded by sulfonic acid sites ($SO_3^-$) to give a cation-selective polyelectrolyte porous bed with an ion exchange capacity ($I_{EC}$) of 3.0 meq/g and an ionic conductivity of 0.09 S/cm. The Pt loading was estimated to be 16.32 wt% from the $SO_3^-$ ions on the surface of the sulfonated PS fibers, which interact with the cationic platinum complex, $Pt(NH_3)_4^{2+}$, at a ratio of 3:1 based on steric hindrance and the arrangement of interacting ions. This is in good agreement with the Pt loading of 15.82 wt% measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The Pt-loaded sulfonated PS media showed an ionic conductivity of 0.32 S/cm. The in-situ metallized platinum provided a nano-sized and strongly-bound catalyst in robust porous media, which highlights its potential use in various electrochemical and catalytic systems.