• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.66-71
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• 2008

A new route to phthalocyanine complexes were developed to synthesize these products by fusion in the absence of solvent. This new method of synthesis without using solvent has advantages over the conventional synthetic methods since there are no risk of explosion and formation of harmful vapor from organic solvent. Reaction of PcFe with axial ligands such as $PcFe(4-VP)_2$[Pc: Phthalocyanine, 4-VP: 4-Vinylpyridine] and $PcFe(VIM)_2$[VIM: 1-Vinylimidazole] afforded powderlike, pure dark greenish blue colored products. The resulted products are soluble in $CH_2Cl_2$ and found to be complexes of the type $PcFeL_2$. Spectral properties were studied with ATR-FTIR and UV/Vis. Thermal and electrical characterization was also performed. Phthalocyanine complexes exhibit useful properties such as UV/Vis blocking, antistatic characteristics and excellent thermal stability and we anticipate various applicability in numerous products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4689-4695
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• 2011

Nanodiamond is a relatively new nanomaterial with broad prospects for application. In this paper, a variety of methods were used to analyze comprehensively chemicophysics properties of the detonation monocrystalline and synthetic polycrystalline nanodiamond, XRD spectroscopy, EDS, HRTEM, FTIR, Raman spectroscopy, TGA-DTA and BET. The results show that the monocryctalline detonation nanodiamond particles are spherical or elliptical shape of 4nm ~ 6nm grain size and the polycryctalline synthetic nanodiamond particles are angular shape of 80nm ~ 120nm grain size. The surface of the monocrystalline and polycrystalline nanodiamond contain hydroxy, carbonyl, carboxyl, ether-based resin, and other functional groups. The phase transition temperature of the monocrystalline detonation nanodiamond in the $N_2$ is about $650^{\circ}C$.

• Polymer(Korea)
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• v.30 no.2
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• pp.158-161
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• 2006

Recently the application of plastic optical fiber (POF) in automotives and planes demands the heat-resistant and high refractive index con materials. We synthesized polyglutarimides (PGIs) via imidization of PMMA with primary amines under high pressure and high temperature and investigated thermal and optical properties by varying the molar ratio of amines and the type of amines (ethyl amine vs. isopropyl mine). The degree of imidization was calculated based on the peak intensity in $^1H$ NMR and FTIR. We found that the glass transition temperature $(T_g)$ of PGIs increased over $30^{\circ}C$ compared to the traditional core materials in POF, PMMA, and they are stable up to $300\sim400^{\circ}C$. PGIs anthesized with ethyl mine show the better heat resistance than those with isopropyl amines. Additionally, they show the comparable transparency and higher refractive index than PMMA. It implies that they can be utilized as the excellent photo-efficient and heat-resistant core materials in POF.

• Polymer(Korea)
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• v.35 no.5
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• pp.395-401
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• 2011

MWNT/PMMA and MWNT/PDMAEMA nanocomposites were prepared using an atom transfer radical polymerization (ATRP). The FTIR and XRD analysis results showed that the nanocomposites were composed of MWNTs grafted by either PMMA(PMMA-g-MWNTs) or PDMAEMA(PDMAEMA-g-MWNTs). A controlled living radical polymerization of ATRP was characterized by the thermogram analysis for the nanocomposites. The morphologies of prepared nanocomposites were analyzed by transmission electron microscopy. Raman analysis results for the nanocomposites showed that there occurred covalent bonding between acrylic polymers and MWNTs.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.522-533
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• 2014

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of $Ag^+$ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of $Ag^+$ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.555-563
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• 1999

Impregnation of phosphorous additiers into graphite bulk was studied with the goal of enhancing the effectiveness of oxidationprotection. In addition graphite acid washing was carried out prior to the impregnation further to improve oxidation resistance. Observation of the oxidation rate for raw graphite(Raw) impregnated graphite with tri-butyl phsophate on raw block(RP) and impregnated graphite on acid-treated graphite(AP) in air are reported. The phsophorus residue adsorbed on the graphite surface at active sites was determined by FTIR, XRS, TGA techniques. AP with tri-butyl phosphate was found to result in both 30% reduction in oxidation rate at 1000$^{\circ}C$ compared to Raw and increase of 120$^{\circ}C$ in oxidation temperature From the samples of oxidation rate of each specimen in Arrhenius plot it can be said that the present oxidation resistance origninates from the change of chemical reaction modesw neigther by acid-washing treatment nor phsophate impregnation

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1437-1443
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• 2018

In this work, $SnO_2$ modified with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) separately and combined sensitized by using the co-precipitation method and their sensing behavior toward ethanol vapor at room temperature were investigated. An interdigitated electrode (IDE) gold substrate is very expensive compared to a fluorine doped tin oxide (FTO) substrate; hence, we used the latter to reduce the fabrication cost. The structure and the morphology of the studied materials were characterized by using differential thermal analyses (DTA) and thermogravimetric analysis (TGA), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller surface area and Barrett-Joyner-Halenda (BJH) pore size measurements. The studied composites were subjected to ethanol in its gas phase at concentrations from 10 to 200 ppm. The present composites showed high-performance sensitivity for many reasons: the incorporation of $SnO_2$ and CNTs which prevents the agglomeration of rGO sheets, the formation of a 3D mesopourus structure and an increase in the surface area. The decoration with rGO and CNTs led to more active sites, such as vacancies, which increased the adsorption of ethanol gas. In addition, the mesopore structure and the nano size of the $SnO_2$ particles allowed an efficient diffusion of gases to the active sites. Based on these results, the present composites should be considered as efficient and low-cost sensors for alcohol.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.275-279
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• 2012

(3-mercaptopropyl)trimethoxysilane (MPTMS) was used as a silylation agent, and modified silica nanoparticles were prepared by solution polymerization. 2.0 g of silica nanoparticles, 150 ml of toluene, and 20 ml of MPTMS were put into a 300 ml flask, and these mixtures were dispersed with ultrasonic vibration for 60 min. 0.2 g of hydroquinone as an inhibitor and 1 to 2 drops of 2,6-dimethylpyridine as a catalyst were added into the mixture. The mixture was then stirred with a magnetic stirrer for 8 hrs. at room temperature. After the reaction, the mixture was centrifuged for 1 hr. at 6000rpm. After precipitation, 150 ml of ethanol was added, and ultrasonic vibration was applied for 30 min. After the ultrasonic vibration, centrifugation was carried out again for 1 hr. at 6000rpm. Organo-modification of silica nanoparticles with a ${\gamma}$-methacryloxypropyl functional group was successfully achieved by solution polymerization in the ethanol solution. The characteristics of the ${\gamma}$-mercaptopropyl modified silica nanoparticles (MPSN) were examined using X-ray photoelectron spectroscopy (XPS, THERMO VG SCIENTIFIC, MultiLab 2000), a laser scattering system (LSS, TOPCON Co., GLS-1000), Fourier transform infrared spectroscopy (FTIR, JASCO INTERNATIONL CO., FT/IR-4200), scanning electron microscopy (SEM, HITACHI, S-2400), an elemental analysis (EA, Elementar, Vario macro/micro) and a thermogravimetric analysis (TGA, Perkin Elmer, TGA 7, Pyris 1). From the analysis results, the content of the methacryloxypropyl group was 0.98 mmol/g and the conversion rate of acrylamide monomer was 93%. SEM analysis results showed that the organo-modification of ultra-fine particles effectively prevented their agglomeration and improved their dispensability.

• Polymer(Korea)
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• v.37 no.4
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• pp.437-441
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• 2013

A novel sulfonate flame retardant, 1,3,5,7-tetrakis(phenyl-4-sodium sulfonate)adamantane (FR-A), was successfully synthesized from 1-bromoadamantane in sequential four-step reactions involving Fiedel-Crafts phenylation, sulphonation, hydrolysis, and neutralization. The success of synthesis was confirmed by FTIR spectra, $^1H$ NMR spectra, elemental analyses and mass spectra. The effect of FR-A on the flame retardacy of polycarbonate (PC) has been studied. Limiting oxygen index (LOI) and thermogravimetric analysis (TGA) showed that this novel sulfonate flame retardant had effective flame retardancy on polycarbonate (PC). With a small amount (0.08 wt%) of FR-A, the flame retardancy of PC was improved obviously, which got to UL 94 V-0 rating. TGA and DTA curves demonstrated that the additive raised the degradation rate of PC by promoting the quick formation of an insulating carbon layer on the surface, and confirmed that the flame retardant mechanism of PC/FR-A system was similar to potassium diphenylsulfone sulfonate (KSS).

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.2
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• pp.163-170
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• 2002

In this paper, silk fibroin (SF)/polyurethane (PU) blend films were fabricated to develop a new biomaterial for biomedical applications. These blend films were prepared using formic acid as a cosolvent, and structural characteristics and properties of blend films were investigated. FTIR results suggested that there was no specific interaction between SF and PU, implying molecular immiscibility in SF/PU blend films. Furthermore, it was revealed by XRD method that the crystalline region of blend components was not perturbed by counterpart polymers. The degree of phase separation of SF/PU blend films was diminished by increasing PU content in blend. Especially, the blend with 70% content of PU showed no evidence of macro-phase separation in SEM observation. However, SF/PU blend (70/30) was revealed to be phase-separated in a lower dimension confirmed by DMTA measurement. TGA result showed that thermal decomposition temperature of blend film was slightly decreased compared to those of SF and PU polymer itself, Though mechanical properties of SF/PU blend films were not good enough due to the solvent, blood compatibility of PU can be enhanced markedly by mixing with SF for SF/PU blend film.