• Applied Chemistry for Engineering
• /
• v.24 no.2
• /
• pp.196-200
• /
• 2013

We conducted investigation on polymeric binders for anti-static coating agent which can maintain stability under the high-voltaic condition. Various polyesters composed of polyethylene glycol (PEG) and polypropylene glycol (PPG) were synthesized and studied in term of the variation in the surface resistance of the film made from coating solution composed of a conductive polymer and these polyesters as a binder. We found that the surface resistance displayed $10^7{\sim}10^8{\Omega}/{\square}$ regardless of chemical composition of binders under the potential of 10 V. Whereas, the surface resistance surged to higher than $2{\times}10^{10}{\Omega}/{\square}$ when 1000 V was applied, rendering it improper for anti-static purpose. When 1,4 butanediol (BD) was incorporated into polyesters ([PEG]/[PPG]/[BD] = 25.0/67.5/7.5), the surface resistance showed $2.8{\times}10^9{\Omega}/{\square}$ under 1000 V, acceptable for anti-static application. These observations may indicate that the hydrophobic nature of BD makes a significant contribution to the surface resistance at a high positive potential.

• Membrane Journal
• /
• v.28 no.1
• /
• pp.75-82
• /
• 2018

Forward osmosis (FO) desalination system has been highlighted to improve the energy efficiency and drive down the carbon footprint of current reverse osmosis (RO) desalination technology. To improve the trade-off between water flux and salt rejection of thin film composite (TFC) desalination membrane, thin film nanocomposite membranes (TFN), in which nanomaterials as a filler are embeded within a polymeric matrix, are being explored to tailor the separation performance and add new functionality to membranes for water purification applications. The objective of this article is to develop a graphene nanocomposite membrane with high performance of water selective permeability (high water flux, high salt rejection, and low reverse solute diffusion) as a next-generation FO desalination membrane. For advances in fabrication of graphene oxide (GO) membranes, layer-by-layer (LBL) technique was used to control the desirable structure, alignment, and chemical functionality that can lead to ultrahigh-permeability membranes due to highly selective transport of water molecules. In this study, the GO nanocomposite membrane fabricated by LBL dip coating method showed high water flux ($J_w/{\Delta}{\pi}=2.51LMH/bar$), water selectivity ($J_w/J_s=8.3L/g$), and salt rejection (99.5%) as well as high stability in aqueous solution and under FO operation condition.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.4
• /
• pp.584-594
• /
• 2014

To increase of surface hydrophilicity of polymeric thin films is an important approaching technique for introduction of self-cleaning and/or antifogging properties on the surfaces of those films. In general, hydrophilic surface can be produced by coating non ionic surfactants or by increasing surface energy. Various non-ionic surfactants, such as Tween, Span, and PEG-PPG block copolymers were selected for our experiments, because they are cheap and well soluble in toluene system as well as they contain several reactive hydroxy fuctional groups with coupling agents. Blending conditions influence the PET film surface hydrophilicities. However, the introduction of only these surfactants on the surface of PET films did not show the high durability of hydrophilic properties after washing with water. To improve the durability two types of coupling agents such as epoxide and diisocyanate were adopted. Contact angle of water on hydrophilically coated PET film surface with 6 wt% of isophrone diisocyanate(IPDI) containing coating solution was reached to $8.7^{\circ}$, which was an indirect evidence for very high surface hydrophilicity. A light(500 nm of wavelength) transmittance value of coated PET film was changed only from 87% to 85% with keeping a good transparent property. This film can be usable for self-cleaning film industries.

• Korean Journal of Materials Research
• /
• v.4 no.4
• /
• pp.466-471
• /
• 1994

The polymeric titania sol was prepared via partial hydrolysis of titanium isopropoxide and its characteristics were investigated. The effect of solvent, catalyst and water content on the sol stability was investigated. The shear viscosities of sol solution at different temperatures were measured to determine the gel time. Employing the spin coating technique, optically clear and transparent titanium oxide thin film was fabricated. Even after doped with second-order nonlinear optical(NL0) active monomers, the film quality was maintained very homogeneous. The film was corona-poled under 3~ 5kV at 50~$100^{\circ}C$ range. The electro-optic coefficient, $r_{33}$ was measured to be 1.5~5pm/V using the wavelength, 632.8nm from He-Ne laser.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.781-783
• /
• 2009

We achieved high efficiency and long lifetime in small-molecule organic light-emitting diodes using a blend of polyaniline-based conducting polymer and a perfluorinated ionomer as a hole injection layer (HIL). The HIL formed by single spin coating greatly enhanced the surface work function and thus the hole injection from the anode, which resulted in great improvement in device luminous efficiency. We find that the solution processed HIL outperforms the conventional vacuum-deposited small molecule HIL in terms of the device performance.

• Tribology and Lubricants
• /
• v.30 no.6
• /
• pp.343-349
• /
• 2014

Currently, in order to resist the scratching of the fuel rod surface while fabricating the fuel assembly of the light-water nuclear reactor, we use a solution of nitrocellulose, an explosive material, as a dry lubricant along with its solvent. However, the demand for developing safe and harmless aqueous alternative materials for environment-conservation and field-worker safety has increased. In this study, we demonstrate the preparation of a novel aqueous resin composite using a formulation of aqueous polymeric resin, alcoholic solvent, and water. Subsequently, we characterize this composite on the basis of hardness, adhesive property, and water solubility using plates similar to the fuel rod material. The insertion test of a fuel rod coated with the YS-3 composite shows load values of $18.8-20.5kg/cm^2$, which is comparable with $18.8-20.5kg/cm^2$ of the nitrocellulose coating agent. In addition, the depth and width of longitudinal scratches caused by the YS-3 composite test are 50% higher than those of the standard. We can develop a harmless and safe aqueous dry lubricant to replace the existing NC products through field testing of 264 pieces of fuel rods, after producing 350 kg of the YS-3 prototype. The scratch test for the rod surface showed that weight of chip of YS-3 prototype was smaller than that of NC before and after solvent treatment, indicating the properties of YS-3 prototype was comparable to the counterpart.

• Polymer(Korea)
• /
• v.34 no.6
• /
• pp.565-573
• /
• 2010

Copoly(2-(dimethylamino)ethyl methacrylate)(DAEMA)/butyl acrylate (BA) and copoly(methyl methacrylate)(MMA)/BA/2-(cinnamoyloxy)ethyl methacryate (CEMA), which were cross-linked with dibromoalkane and UV irradiation, respectively, were prepared for the precursors of interpenetrating polymer network (IPN) humidity-sensitive films. 3-(Triethoxysilyl)propyl cinnamate (TESPC) was used as a surface-pretreating agent for the attachment of IPN-polyelectrolyte to the electrode surface by UV irradiation. Humidity sensitive polymeric thin films with an IPN structure were prepared by crosslinking reactions of copoly(DAEMA/BA) with 1,4-dibromobutane (DBB) and copoly(MMA/BA/CEMA) by UV-irradiation. The anchoring of an IPN-polyelectrolyte into the substrate was carried out via the photochemical $[2{\pi}+2{\pi}]$ cycloaddition. The resulting humidity sensors showed a high sensitivity in the range of 20~95%RH and a small hysteresis (<1.5%RH). The response time for adsorption and desorption process at 33~94%RH was 48 and 65 s, respectively, indicating a fast response. The effects of the concentration of copolymers, molar ratio of crosslinking agents and time of the precursor solution for dip-coating on their humidity sensitive properties including water durability were investigated.