• Elastomers and Composites
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• v.54 no.1
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• pp.14-21
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• 2019

Main-chain/side-chain liquid crystalline polymers (MCSCLCPs) combined with an azobenzene group and a cholesteryl group were synthesized to impart light and temperature sensitivity to the polymer. The polymers were designed with the azobenzene unit as the mesogenic group of the main-chain and various compositions of the azobenzene and cholesteryl units as the mesogenic group of the side-chain. The chemical structures and physical properties of the synthesized polymers were investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and ultraviolet-visible (UV-Vis) spectroscopy. All the MCSCLCPs were amorphous and exhibited enantiotropic liquid crystal phases; these polymers achieved the nematic phase with increasing content of the azobenzene group and exhibited the cholesteric phase with weak liquid crystallinity as the content of the cholesteryl group was increased. Furthermore, the polymers containing the azobenzene group showed photoisomerization when exposed to UV-Vis light, and the CP-A3C7 and CP-A5C5 polymers exhibited thermochromism in the temperature range of the liquid crystal phase.

• Clean Technology
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• v.26 no.4
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• pp.251-256
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• 2020

The biocompatibility and plasmonic properties of Au nanoparticles make them useful for photothermal therapy, drug delivery, imaging, and many other fields. This study demonstrated a novel, facile, economic, and green synthetic method to produce gold nanoparticles. Gold nanoparticles (AuNPs) with spherical and triangular shapes were effectively synthesized using only Schisandra chenesis fruit extract as the capping and reducing agent. The shape of the AuNPs could be engineered simply by adjusting the molar concentration of HAuCl4 in the reaction mixture. The as-synthesized AuNPs were characterized using UV-VIS spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and energy dispersive X-ray analysis (EDXA). This study revealed that by using the HAuCl4 concentration in the AuNP synthesis, the shape and size of the AuNPs could be controlled by the concentration of HAuCl4 and Schisandra chinensis fruit extract as a surfactant. The as-synthesized AuNPs samples had sufficient colloidal stability without noticeable aggregation and showed the predominant growth of the (111) plane of face-centered cubic gold during the crystal growth. The catalytic efficiency of the AuNPs synthesized using Schisandra chenesis fruit extract was examined by monitoring the catalytic reduction of 4-nitrophenol to 4-aminophenol using Ultraviolet-visible spectroscopy (UV-Vis spectroscopy). The synthesized AuNPs showed good catalytic activity to reduce 4-nitrophenol to 4-aminophenol, revealing their practical usefulness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.132-138
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• 2023

Doped and undoped-BiVO₄ samples with different elements (Li, Mg) and amounts were synthesized with a hydrothermal method. The synthesized samples were characterized using various techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffusion reflectance spectroscopy (UV-Vis DRS), and photoluminescence (PL) spectroscopy. Photocatalytic activity of the samples was evaluated by measuring the degradation of methyl blue (MB) under visible light irradiation. The results indicated that the incorporation of Mg and Li into BiVO₄ caused lattice distortion, the presence of surface hydroxyl groups, a narrower band gap, and a reduced recombination ratio of photo-induced electron-hole pairs. Notably, the photocatalytic activity of Mg5%-Li5% co-doped BiVO₄ sample exhibited a significant improvement compared to that of undoped BiVO₄ sample.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.418-418
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• 2012

We fabricated a new type of hybrid film using molecular layer deposition (MLD). The MLD is a gas phase process analogous to atomic layer deposition (ALD) and also relies on a saturated surface reaction sequentially which results in the formation of a monolayer in each sequence. In the MLD process, polydiacetylene (PDA) layers were grown by repeated sequential surface reactions of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet (UV) polymerization under a substrate temperature of $100^{\circ}C$. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the hybrid films. Polymerization of the hybrid films was confirmed by infrared (IR) spectroscopy and UV-Vis spectroscopy. Composition of the films was confirmed by IR spectroscopy and X-ray photoelectron (XP) spectroscopy. The titanium oxide cross-linked polydiacetylene (TiOPDA) hybrid films exhibited good thermal and mechanical stabilities.

• Analytical Science and Technology
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• v.13 no.3
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• pp.282-290
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• 2000

In this study, polymer additives were extracted and separated by Soxhlet extraction method and the dissolution-precipitation method from a polycarbonate (optical grade) which completely absorbed UV light below 390 nm. Analytical techniques such as UV-Vis spectroscopy, FT-IR, and HPLC were applied to analyze additives in polycarbonate. Separated materials from the polycarbonate may be a complex mixture containing additives such as UV stabilizer, antioxidants (primary and secondary), monomers, and oligomers. Several compounds such as bisphenol A, Irganox 1010, and Cyasorb UV-5411 were identified by chromatograms and UV spectra obtained from RP HPLC analysis using Bondapak $C_{18}$ column, methanol mobile phase, and a photodiode array (PDA) detector. Also, the content of UV-5411 in the polycarbonate was about 0.12 wt% by a quantitative analysis through UV spectroscopy.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.337-344
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• 2014

In this paper, we have examined the interaction of low bandgap polymer {poly(2-heptadecyl-4-vinylthieno[3,4-d]thiazole)(PHVTT)} with ionic liquids. Further, we have studied the temperature dependent interactions between the ionic liquids [tri-butyl methyl ammonium methyl sulfate ([TBMA][$MeSO_4$]), methyl imidazolium chloride ([MIM]Cl) and butyl methyl imidazolium chloride ([BMIM]Cl)] and polymer using UV-vis spectroscopy, FT-IR spectroscopy, photoluminescence (PL) spectroscopy, as a function of temperature at 21, 28, 32, $37^{\circ}C$. These experimental results suggest that interactions of polymer with ionic liquids ([MIM]Cl, [TBMA][$MeSO_4$]) showed weak interactions by increasing temperature but [BMIM]Cl has no significant effect with increase in temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.29-36
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• 2010

The spectroscopic characteristics of synthetic and natural emeralds were investigated by UV-Vis and FTIR spectroscopy before and after heat treatment. The Mo and Co for synthetic flux and C1 for synthetic hydrothermal emeralds have been detected by X-ray fluorescence analysis. In the region of UV-Visible, the absorption of emerald from Colombia was generally increased after the heat treatment. The peak which related to C1 component in the $3000-2600cm^{-1}$ was shown in the hydrothermal synthetic emeralds by FTIR spectroscopy. The $2358cm^{-1}$ peak which originates from $CO_2$ was decreased after the heat treatment in the natural emerald. This was corresponded with the changes of gas element after heat treatment.

• Carbon letters
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• v.10 no.4
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• pp.325-328
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• 2009

This cycloaddition of [70]fullerene with methyl azidoacetate in benzene under ultrasonic irradiated condition afforded the closed [5,6]-bridged aziridino[70]fullerene derivative, which was unusual product of cycloaddition to the 5,6-junction of fullerene. Its structure was determined by FAB-MS, UV-vis, $^1H-$ and $^{13}C$-NMR spectral data. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films were self-assembled using the layer-by-layer method on the reactive of glass slides functionalized with 3-mercaptopropyl trimethoxysilane. The functionalized glass slides were alternately soaked in the solution containing closed the [5,6]-bridged aziridino[70]fullerene and 4-aminothiophenoxide/hexanethiolate-protected gold nanoparticles. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films have grown up to 5 layers depending on the immersion time. The self-assembled nanoparticle multilayer films were characterized using UV-vis spectroscopy showed that the surface plasmon band of gold at 527 nm gradually became more evident as successive layers were added to the films.

• Textile Coloration and Finishing
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• v.21 no.5
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• pp.51-57
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• 2009

Since heavy metal pollution is a significant global environmental problem and very dangerous to human health, the improved methods for detecting heavy metals are required recently. Colorimetric chemosensors are now considered as one of the most effective analytical method used in the environment monitoring. New direct dyes having the function of colorimetric chemosensors were synthesized. When metal ions such as $Al^{3+}$, $Ca^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Cu^{2+}$, $Fe^{2+}$, $Fe^{3+}$, $Hg^{2+}$, $Li^+$, $Mg^{2+}$, $Na^+$, $Ni^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ were added each solution of new direct dyes, the color of solution was changed and can be easily detected with naked eyes without expensive experimental equipment such as atomic absorption spectrometer (AAS) or inductively coupled plasma?mass spectrometer (ICP-MS). The new benzidine analogues were diazotized and reacted with couplers such as H-acid, J-acid, Chromotropic acid, Nevill-winther acid and gamma acid to synthesize new direct dyes. The structures of the new direct dyes were confirmed by high resolution mass spectrometer (FAB ionization) and evaluated with UV-Vis spectroscopy. The UV-VIS spectroscopy was measured for the dye solutions by adding various concentrations of metal ions. It was observed that the absorbance in UV-Vis spectra was changed as the heavy metal ions were added.

• Journal of Powder Materials
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• v.27 no.3
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• pp.233-240
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• 2020

Nano-sized ZnSe particles are successfully synthesized in an aqueous solution at room temperature using sodium borohydride (NaBH₄) and thioglycolic acid (TGA) as the reducing agent and stabilizer, respectively. The effects of the mass ratio of the reducing agent to Se, stabilizer concentration, and stirring time on the synthesis of the ZnSe nanoparticles are evaluated. The light absorption/emission properties of the synthesized nanoparticles are characterized using ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy, and particle size analyzer (PSA) techniques. At least one mass ratio (NaBH4/Se) of the reducing agent should be added to produce ZnSe nanoparticles finer than 10 nm and to absorb UV-vis light shorter than the ZnSe bulk absorption wavelength of 460 nm. As the ratio of the reducing agent increases, the absorption wavelengths in the UV-vis curves are blue-shifted. Stirring in the atmosphere acts as a deterrent to the reduction reaction and formation of nanoparticles, but if not stirred in the atmosphere, the result is on par with synthesis in a nitrogen atmosphere. The stabilizer, TGA, has an impact on the Zn precursor synthesis. The fabricated nanoparticles exhibit excellent photo-absorption/discharge characteristics, suggesting that ZnSe nanoparticles can be alloyed without the need for organic solutions or high-temperature environments.