• Polymer(Korea)
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• v.32 no.4
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• pp.377-384
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• 2008

In this study, the microsphere silicone polymer beads were synthesized by UV irradiation and alkoxy hydrolysis. The coefficient of variation (CV) of microsphere silicone polymer beads were decreased with increasing UV intensity, reaction time. The mean particle diameter, refractive index, and pH value were $4.1{\mu}m$, 1.43 and 7.5, respectively. Also, the true and bulk specific gravity, moisture content were 1.30, and 0.40, below 2%. The mean particle diameter and CV were the lowest at 0.1 wt% hexamethyldisilazane (HMDS) and their roundnesses were $0.95{\sim}0.98{\mu}m$ values. The particle dispersion index of microsphere silicone polymer beads was 4.92 at 450 W, 90 min and the yield was increased to 11.3% at 20 wt% methyltrimethoxysilane (MTMS). The mean particle diameter was decreased with increasing the stirring rate and reaction temperature.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1647-1652
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• 2012

With the objective to design and synthesis of Schiff's base symmetrical liquid crystal dimmers and to study the effect of molecular structure variation ($o-ortho$, $m-meta$, $p-para$) and change in alkoxy terminal chain length on mesomorphic properties of liquid crystals, We have synthesized Schiff base dimers from dialdehyde derivative containing 2-hydroxy-1,3-dioxypropylene as short spacer with aniline derivatives having different lengths of terminal alkoxy chains ($n$ = 5, 7, 9). The chemical structure of the final products was characterized by proton nuclear magnetic resonance ($^1H$ NMR) spectroscopy and fourier transform infrared (FT-IR) spectroscopy. The mesomorphic properties and optical textures of the resultant dimers were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The existence of smectic A phase transition was confirmed by the observation of batonnets and fan shaped textures in optical microscopy when compound were heated from crystalline phase. All of the dimers of this series, with the exception of $\mathbf{2S_5}$ -ortho, -meta, -para, were thermotropic liquid crystal. The compound $\mathbf{2S_9}$ -meta was monotropic, while the rest were enantiotropic. It was found that the change in terminal alkoxy chain length has pronounced effect on the mesomorphic properties. The temperature range of smectic A phase window widens with increasing alkoxy chain length.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.69-71
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• 2000

The herbicidal activities ($pI_{50}$) with alkoxy (RO-) groups on the azomethine nitrogen atom in 5-(2,3-dihydro-2,2-dimethylbenzothiophene-7-yl)-2-(1-(alkoxyimino)butyl)-3-hydroxy-2-cyclohexene-1-one derivatives against various weeds were measured in the flooded and in the paddy conditions. Particularly, i-propoxy subsutuent, 5 of them showed excellent herbicidal activity at a rate of 4kg/ha with pre-emergence against barnyard grass (Echinochloa crus-galli) with good selectivity on rice plant (Oryza sativa). The results of the structure-activity relationships (SAR) analyses are shown that the alkyl subsituents with higher hydrophobicity (logp>0) and electron donating (${\sigma}^*<0$) group as a new substrate rather than alkoxy substituents seems to be contribute to the herbicidal activity with pre-emergence.

• 한국정보디스플레이학회:학술대회논문집
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• 2001.08a
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• pp.209-212
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• 2001

We report the synthesis and characterization of new alkoxy substituted spirobifluorene derivatives. The spiro compounds having alkoxy hydrocarbon chains were readily soluble in common organic solvents, having improved film-forming properties and had a significantly reduced tendency to crystallize, resulting in increasing their service lifetime. The results of DSC showed that it was amorphous. The optical and electroluminescent spectra were characterized. Electroluminescence (EL) properties of three-layer light emitting diodes (LED) of $ITO/TPD/spirobifluorene/Alq_3/LiF/Al$ as the active layer were characterized. Blue emission peaking of the EL spectrum of the three-layer device at 402 nm and a luminance of 3,125 $cd/m^2$ were achieved at a drive voltage 12.8 V. The luminous efficiency was obtained to be 1.7 lm/W. The color coordinate in CIE chromaticity is (0.16, 0.09), which is in a pure blue region. The external quantum efficiency was obtained to be 2.0%. The results indicate that the spirobifluorene compounds having alkoxy hydrocarbon chains are strongly potential blue emitters for LED applications.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1939-1944
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• 2007

New liquid crystalline (biphenylcarbonyloxy)benzoates with an achiral swallow-tail derived from 3-alkoxy-2- (alkoxymethyl)-1-propanol [(ROCH2)2CHCH2OH, R = Me, Et, Pr, Bu] were prepared. These liquid crystals exhibited the phase sequence (I-SmA-SmCalt-(SmCX)-Cr) and showed antiferroelectric-like Smectic C phase (SmCalt) at temperature lower, and temperature range broader than do the compounds containing a branched alkyl group as a swallow-tail. The temperature ranges of antiferroelectric phase were found to be 30-90 oC and crystallization temperatures were 4-60 oC. The binary mixture of an achiral swallow-tailed liquid crystal and a chiral antiferroelectric liquid crystal, (S)-MHPOBC showed antiferroelectric smectic C phase at temperature much lower than the single chiral antiferroelectric liquid crystal does.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.35-35
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• 2010

Understanding the mechanistic details of heterogeneous catalytic reactions will provide a way to tune the selectivity between various competing reaction channels. In this regard, catalytic decomposition of alcohols over the rutile $TiO_2$(110) surface as a model oxide catalyst has been studied to understand the reaction mechanism employing the temperature-programmed desorption (TPD) technique. The $TiO_2$(110) model catalyst is found to be active toward alcohol dehydration. We find that the active sites are bridge-bonded oxygen vacancies where RO-H heterolytically dissociates and binds to the vacancy to produce alkoxy (RO-) and hydroxyl (HO-). Two protons adsorbed onto the bridge-bonded oxygen atoms (-OH) readily react with each other to form a water molecule at ~500 K and desorb from the surface. The alkoxy (RO-) undergoes decomposition at higher temperatures into the corresponding alkene. Here, the overall desorption kinetics is limited by a first-order decomposition of intermediate alkoxy (RO-) species bound to the vacancy. We show that detailed analysis on the yield and the desorption temperatures as a function of the alkyl substituents provides valuable insights into the reaction mechanism. After the catalytic role of the oxygen vacancies has been established, we employed x-ray photoelectron spectroscopy to further study the surface electronic structure related to the catalytically active defective sites. The defect-related state in valence band has been related to the chemically reduced $Ti^{3+}$ defects near the surface region and are found to be closely related to the catalytic activity of the $TiO_2$(110) surface.

• The Korean Journal of Pesticide Science
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• v.6 no.2
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• pp.58-63
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• 2002

New photodynamic herbicidal 2,3-dihydro-2,2,4,5,6-pentamethylbenzofuran-5-yl, (I) and 2,3-dihydro-2-ethyl-2,4,5,6-tetramethylbenzofuran-5-yl, (II) substituents in 6-benzofury-2-[1-( alkoxyimino )alkyl]-3 hydroxycyclohex-2-en-1-one derivatives were synthesized and their herbicidal activities against rice plant (Oryza sativa L.), barnyard grass (Echinochloa crus-galli) and pickerel weed (Monochoria vaginalis presl.) were measured under submerged pre and post-emergence conditions. Particularly, a series of (I) compounds showed good selective herbicidal activities between the 3 leaf stage of rice plant and barnyard grass at rates of $0.25{\sim}0.0007kg/ha$. The structure activity relationships (SAR) on the herbicidal activity with changing N-alkoxy groups were discussed quantitatively. According to the SAR results, it was expected that the selectivity factor between seed of rice plant and barnyard grass should be rely on the N-alkoxy groups with bigger dipole moment and bigger (or smaller) $B_3$ constant than optimal value $(B_3)_{opt.}=4.41{\AA}$. Compared with (I), the (II) substituents showed more superior herbicidal activities.

• Journal of Adhesion and Interface
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• v.2 no.4
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• pp.1-9
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• 2001

Silicone sealants are composed of polymer, plasticizer, crosslinker, catalyst and filler. Types and compositions of components are effected on sealant performances. In recent, use of alkoxy type silicone sealant increased due to environmental advantage. In this study, we investigated effects of component types and ratios on one-part room temperature curable alkoxy type silicone sealant preparation and adhesion properties. Alkoxy type silicone sealants were prepared with various PDMS (polydimethylsiloxane) viscosities. In addition, the effect of plasticizer, crosslinkers, and catalyst on sealant obtained from by mixture of PDMS viscosities of 20000 and 80000 was investigated. Reaction temperature on change of mixing time was observed, and then proper crosslinking systems were found. Adhesion (properties) of silicone sealants were measured. In the sealants preparation, stable reaction was achieved by adjusting composition variance ratio in the sealant mixture temperature below $40^{\circ}C$. The adhesion properties of sealant differ from substrate composition. The order of adhesion strength was glass/glass > glass/aluminum > aluminum/aluminum system. The elongation of sealant was increased as polymer viscosity and plasticizer content increased. The strength was increased as crosslinker and plasticizer decreased, while catalyst increased.

• Macromolecular Research
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• v.17 no.4
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• pp.218-220
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• 2009

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.896-898
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• 1997