• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1988-1992
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• 2011

Polypropylene (PP)-SEBS/silicate composites with PP content of 35, 40, and 45wt% were fabricated by melt compounding at $200^{\circ}C$, using lab scale Brabender mixer. The content of silicate was fixed at 5wt%. The thermal properties of the PP-SEBS/silicate composites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). The melting temperature of PP-SEBS compound decreased up to $141^{\circ}C$ with SEBS content. TGA result indicates an increase in degradation temperature when the silicate was added in the PP-SEBS compound. The rheological properties of the compounds were measured by dynamic Rheometer. PP-SEBS/silicate composite indicates higher shear thinning and elastic property than PP-SEBS compound. Van Gurp-Palmen analysis was applied in order to certify an increase in elasticity.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.199-208
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• 2019

This study reports water-resistant oil-in-water (O/W) emulsion-based sunscreening formulations prepared using a poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG) triblock polymeric surfactant. As a result of a variety of outdoor recreational activities such as swimming and hiking, consumer needs for development of advanced water-resistant sunscreen formulations are increasing. Water-resistant sunscreens are mostly based on water-in-oil (W/O) emulsions, because they should not be wiped off by water or sweat. However, the W/O emulsion formulations have a disadvantage in that the feeling of use is oily and difficult to remove. On the other hand, the O/W emulsion formulations are excellent in achieving the better skin feel as well as the easier removal. However, it is difficult to provide the O/W emulsion formulations with the water-repelling performance, since re-emulsification likely occurs upon getting touch with water. To solve this problem, this study proposes a O/W emulsion-based sunscreen formulation, a triblock polymeric surfactant having relatively high interfacial tension HLB value (~ 10). This allows the sunscreen formulations to exhibit the improved water repellence function by preventing their re-emulsification. The sunscreen formation system prepared in this study would be useful for diversification of functional sunscreen products, taking advantages of its excellent emulsion stability, UV protection performance, long lasting water-resistant function and selective cleansing effect with only foam cleanser.

• Polymer(Korea)
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• v.39 no.3
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• pp.461-467
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• 2015

This paper reports the combined effects of the triblock copolymer surfactant poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEG-PPG-PEG) and imidazole on the opto-electrical and mechanical properties of poly(3,4-ethylenedioxythiophene) (PEDOT)-based thin films prepared via vapor phase polymerization (VPP) using ferric p-toluenesulfonate as a catalyst. Various PEDOT-based thin films were synthesized using PEG-PPG-PEG and imidazole alone and in combination to compare and correlate their effects on film properties. The improved conductivity of the PEDOT films was higher than $1300S{\cdot}cm^{-1}$ when the surfactant and imidazole were used together. The PEG-PPG-PEG chain length was also varied to identify the best conditions for the VPP-based preparation of PEDOT thin films.

• Elastomers and Composites
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• v.49 no.1
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• pp.13-23
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• 2014

In this work, glycolide, L-lactide and ${\varepsilon}$-caprolactone monomers were polymerized into the triblock copolymers by two step polymerization method and their non-isothermal crystallization behaviors were studied by combination of modified Avrami and Ozawa formula for further analysis of their behaviors. The result showed that PGCLA21 gave the highest value for supercooling analysis and super cooling degree increased with L-lactide content. Crystallization velocity constant, however, showed no significant change. The result of cooling function in specific relative crystallization degree showed that the increase of L-lactide content made an effect on the more enhancement of crystallization velocity of the PGCLA than PGCL. The result of big logF(T) value with the L-lactide content above critical point for PGCLA41 and PGCLA21 showed that bigger cooling velocity needed to gain same crystal size compared with PGCL. This means that it gives negative effect in the increase of crystallization velocity.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.96-104
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• 2015

Fischer Tropsch reaction is one of the interesting topic for renewable and clean energy. Polymerization of carbon monoxide or carbon dioxide with hydrogen over metal supported catalyst can produce long chain hydrocarbons. Synthetic liquid hydrocarbons are promising alternative to fossil fuels. This research work has been focused on the synthesis of Fe based catalyst for Fischer Tropsch reaction. Mesoporous silica (MS) support prepared by a precipitation method using two different washing solution, distilled water (DW) and acid in ethanol solution (ET), and different calcination temperature. Then, Fe/MS was prepared by an incipient wetness impregnation method. All of samples were systematically characterized using various physical and chemical techniques. TEM and XRD analysis were used to ensure that the cubic Ia3d mesostructure is stable after calcination. FTIR spectra are useful to ascertain the existence of template in the support. TPR studies were also used to understand the nature of Fe species and their reducibility. The results reveal that washing the support with distilled water and calcination at $550^{\circ}C$ can efficiently remove the triblock copolymer templates. The existence of template in the support affects the textural properties of all catalyst investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.199-199
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• 2011

The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.75-75
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• 2011

Recently, dye-sensitized solar cell (DSSC) attracts great attention as a promising alternative to conventional silicon solar cells. One of the key components for the DSSC would be the nanocrystalline TiO2 electrode, and the control of interface between TiO2 and TCO is a highly important issue in improving the photovoltaic conversion efficiency. In this work, we applied various interfacial layers, and analyzed their effect in enhancing photovoltaic properties. In overall, introduction of interfacial layers increased both the Voc and Jsc, since the back-reaction of electrons from TCO to electrolyte could be blocked. First, several metal oxides with different band gaps and positions were employed as interfacial layer. SnO2, TiO2, and ZrO2 nanoparticles in the size of 3-5 nm have been synthesized. Among them, the interfacial layer of SnO2, which has lower flat-band potential than that of TiO2, exhibited the best performance in increasing the photovoltaic efficiency of DSSC. Second, long-range ordered cubic mesoporous TiO2 films, prepared by using triblock copolymer-templated sol-gel method via evaporation-induced self-assembly (EISA) process, were utilized as an interfacial layer. Mesoporous TiO2 films seem to be one of the best interfacial layers, due to their additional effect, improving the adhesion to TCO and showing an anti-reflective effect. Third, we handled the issues related to the optimum thickness of interfacial layers. It was also found that in fabricating DSSC at low temperature, the role of interfacial layer turned out to be a lot more important. The self-assembled interfacial layer fabricated at room temperature leads to the efficient transport of photo-injected electrons from TiO2 to TCO, as well as blocking the back-reaction from TCO to I3-. As a result, fill factor (FF) was remarkably increased, as well as increase in Voc and Jsc.

• Journal of Adhesion and Interface
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• v.14 no.2
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• pp.82-87
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• 2013

Preliminary studies on the synthesis of magnetic nanoparticles including nanoporous carbon materials have been done via a direct carbonization process from resol, ferric nitrate and triblock copolymer F127. The results show that the nanoporous magnetite/carbon ($Fe_3O_4$/carbon) with a low $Fe_3O_4$ content (1 wt%) possesses an ordered 2-D hexagonal (p6mm) structure, uniform nanopores (3.6 nm), high surface areas (up to 635 $m^2/g$) and pore volumes (up to 0.48 $cm^3/g$). Magnetite nanoparticles with a small particle size (10.2 nm) were confined in the matrix of amorphous carbon frameworks with superparamagnetic property (7.7 emu/g). The nanoporous magnetite/carbon showed maximum adsorption amount (995 mg/g) of ibuprofen after 24 h at room temperature. The nanoporous magnetite/carbon was separated from solution easily by using a magnet. The nanoporous magnetite/carbon material is a good adsorbent for hydrophobic organic drug molecules, i.e. ibuprofen.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.3
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• pp.114-119
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• 2005

We investigated compatibilizing effects of electrical properties such as charge distributions and electrical breakdown in blends of low density polyethylene (LDPE) / polystyrene (PS) with poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), the triblock copolymer. The blends with $70\;wt\%$ of LDPE and $30\;wt\%$ of PS were prepared through a melt blending in a batch type kneader at a temperature of $220^{\circ}C$ when the SEBS content increased up to $10\;wt\%$. Scanning electron microscopy (SEM) was investigated for observation of morphology of LDPE / PS blends increasing SEBS contents. The morphological observation showed that addition of SEBS results in the domain size reduction of the dispersed PS phase and a better interfacial adhesion between LDPE and PS phases. Measurements of space charge distributions for blends was carried out with pulsed electroacoustic (PEA) method. It was possible to observe that the amount of charge storage in the LDPE / PS blends decreased wiか increasing of SEBS content. The location of SEBS at a domain interface enables charges to move from one phase to the other via domain interface and results in a indicative decrease in the amount of space charge for the LDPE / PS blends with SEBS. Electrical breakdown strength of these blends was observed. It was found that the maximum breakdown strength of the blend was 51.55 kV/mm. These results were better than 38.38 kV/mm of LDPE used electrical insulator for cables and were caused by crystalinity of blends. Because the crystalinity of blends were lower than LDPE, electrical breakdown strength of LDPE / PS blends is higher than that of LDPE. We evaluated the possibility of these blends for insulating material substituted LDPE.