• Journal of Powder Materials
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• v.14 no.3 s.62
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• pp.180-184
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• 2007

The material design and synthesis are of important to modem science and technology. Here, we report the synthesis of multifunctional nanomaterials with different properties: feroelecties $YMnO_3$ and multiferroic materials such as $CoFe_2O_4-YMnO_3,\;Fe_3O_4-YMnO_3,\;CoFe_2O_4-Cd_{0.85}Zn_{0.15}S,\;and\;Fe_3O_4-Cd_{0.85}Zn_{0.15}S$ nano-composites by using a chemical synthesis process. These results provide a simple and convenient synthesis process to produce multifunctional nanocomposites.

• Proceedings of the Korean Magnestics Society Conference
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• 2014.05a
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• pp.148-148
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• 2014

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.338-342
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• 2010

Co, $Fe_3O_4$ and Co/$Fe_3O_4$ nanoparticles were synthesized by a polyol process in order to develop their new applications and improve chemical, magnetic properties. The synthesis involved a polyol process using Fe, Co acetylacetonate as precursors and 1-2 hexadecanediol as the polyol. The synthesized $Fe_3O_4$ and Co/$Fe_3O_4$ nanocomposite particles were monodispersed and self arrayed ranging in size of 8~10 and 10~25 nm, respectively. The Co nanoparticle has a crystallite size of 10~40 nm. The synthesized nanoparticles were characterized by their structural, morphological, compositional and magnetic properties using TEM-EDS, XRD, and PPMS techniques.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.560-563
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• 2008

A modified polyol process is developed to enhance Pt loading during the preparation of Pt/C catalysts. With the help of the zeta potential, the effect of pH on the electrostatic forces between the support and the Pt colloid is investigated. It is shown experimentally that the surface charge on the carbon support becomes more electropositive when the solution pH is changed from alkaline to acidic. However, this change does not affect the electronegative surface charge of Pt colloids already attained and stabilized by glycolate anions. This new behavior caused by the change in the solution pH accounts for the enhanced yield of the process and does not affect the Pt particle size. All our experimental results reveal that this simple modification is a cost effective method for the synthesis of highly Pt loaded Pt/C catalysts for fuel cells.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.61-66
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• 2012

Bismuth(Bi) nanoparticles were synthesized at room temperature by a modified polyol process using bismuth(III) carbonate basic as precursor. In addition, some characteristics of the synthesis with respect to the exchange of a capping agent/surface stabilizer and solvent type were observed. When polyvinylpyrroldone was added, the finest Bi nanoparticles were synthesized in diethylene glycol(DEG), while the coarsest nanoparticles were formed in polyethylene glycol(PEG). The particle size immediately after synthesis was proportionate to final particle size which was determined by particle growth through coalescence and aggregation during drying. As a result, the finest Bi particles with the diameter range of several tens of nanometers - 300 nm were finally obtained in DEG. Regardless of the type of capping agent/surface stabilizer, extensive coalescence and aggregation behavior occurred in PEG, resulting in final products agglomerated with coarse particles.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.50-50
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• 1999

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1039-1042
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• 2008

In order to increase a functionality, OH value, for a recycled polyol prepared from the glycolysis reaction of a waste polyurethane rigid foam(PUR), the effect of an addition of pentaerythritol(PEN, functionality(f)=4) or sorbitol(SOR, f=6) to the its glycolysis reactor on the prepared polyol functionality and the mechanical properties of the polyurethane prepared using it was investigated. The OH values increased from 2.2 for a virgin to 2.8 for the recycled polyol. There was an increase in the mechanical properties including dimensional stability for PUR prepared using the recycled polyol, in which the increased OHs provided higher crosslinking density during PUR synthesis. In addition, the amount of the recycled polyol in the polyol system increased to from 8 to 20 wt% to give better mechanical properties to the PUR.

• Journal of Adhesion and Interface
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• v.11 no.3
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• pp.100-105
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• 2010

In this study, polyurethane dispersion was prepared by polyester polyol, 4,4-dicyclohexylmethane diisocyanate ($H_{12}MDI$), dimethylolpropionic acid (DMPA), and monomeric diol. The effect of various monomeric diol, polyol/monomeric diol molar ratio and DMPA contents on the properties of polyurethane dispersion were investigated. As the molecular weight of monomeric diol and monomeric diol molar ratio increased, $T_g$ gradually increased. And when DMPA contents increased, also $T_g$ gradually increased. In the results of mechanical properties, when the molecular weight of monomeric diol, monomeric diol molar ratio of polyol/monomeric diol and DMPA contents increased, tensile strength was increased. Finally, optimum peel strength obtained when polyol/monomeric diol ratio was 8 : 2.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.93-100
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• 2005

8 functionality photocurable polyester polyol modified hyperbranched methacrylates of two types were prepared from trimellitic anhydride, glycidyl methacrylate, and 4 functionality polyester polyol of two types. The physical properties of photocurable polyester polyol modified hyperbranched methacrylate were investigated. Thermal stability obtained by using TGA showed that HBMA-2 (hyperbranched methacrylate-2) was superior to the HBMA-1 (hyperbranched methacrylate-1). Hardness, abrasion resistance and tensile strength of HBMA-2 showed that were also superior to the HBMA-1. Value of yellow index of HBMA-2 showed the higher.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2865-2870
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• 2013

Ni-Ag core-shell nanoparticles were synthesized by polyol process and microemulsion technique successfully. In the polyol process, a chemical reduction method for preparing highly dispersed pure nickel and Ag shell formation have been reported. The approach involved the control of reaction temperature and reaction time in presence of organic solvent (ethylene glycol) as a reducing agent for Ag cation with poly(vinyl-pyrrolidone) (PVP. Mw = 40000) as a capping agent. In microemulsion method, the emulsion was prepared by water/cetyltrimetylammonium bromide (CTAB)/cyclohexane. The size of microemulsion droplet was determined by the molar ratio of water to surfactant (${\omega}_o$). The core-shell formation along with the change in structural phase and stability against oxidation at high temperature heat treatments of nanoparticles were investigated by X-ray diffraction and TEM analysis. Under optimum conditions the polyol process gives the Ni-Ag core-shell structures with 13 nm Ni core covered with 3 nm Ag shell, while the microemulsion method gives Ni core diameter of 8 nm with Ag shell of thickness 6 nm. The synthesized Ni-Ag core-shell nanoparticles were stable against oxidation up to $300^{\circ}C$.