• 통합자연과학논문집
• /
• 제2권2호
• /
• pp.65-68
• /
• 2009

Siloles of considerable current interest, both because of their unusual electronic properties and because of their possible application as electron-transporting materials in devices such as light-emitting diodes (LED's) and chemical sensor. Siloles have been characterized by NMR, FT-IR, and UV-vis absorption spectroscopy. Their optical characteristics have been also investigated using photoluminescence spectroscopy. Thus siloles exhibit a low reduction potential and a low-lying LUMO energy level, attributed to ${\sigma}^*-{\pi}^*$ conjugation arising from the interaction between the ${\sigma}^*$ orbital of the sigma-bonded silicon atom and the $\pi^*$ orbital of the butadiene moiety of the ring.

• 한국환경보건학회지
• /
• 제35권6호
• /
• pp.532-537
• /
• 2009

The tropospheric ozone production mechanism for the gas phase additive oxidation reaction of hydroxyl radical (OH) with isoprene (2-methyl-1,3-butadiene) has been studied using cavity ring-down spectroscopy (CRDS) at total pressure of 50 Torr and 298 K. The applicability of CRDS was confirmed by monitoring the shorter (~4%) ringdown time in the presence of hydroxyl radical than the ring-down time without the photolysis of hydrogen peroxide. The reaction rate constant, $(9.8{\pm}0.1){\times}10^{-11}molecule^{-1}cm^3s^{-1}$, for the addition of OH to isoprene is in good agreement with previous studies. In the presence of $O_2$ and NO, hydroxyl radical cycling has been monitored and the simulation using the recommended elementary reaction rate constants as the basis to OH cycling curve gives reasonable fit to the data.

• Bulletin of the Korean Chemical Society
• /
• 제7권3호
• /
• pp.183-185
• /
• 1986

Self-atom polarizability were calculated for 17 polycyclic aromatic hydrocarbons and their metabolites by LCAO-MO method and examined the relation with the carcinogenicity. It has been found that ${\pi}_{1.2.4}$, the sum of self-atom polarizability of 1, 2 and 4 positions forming trans-butadiene frame in a compound, agree quite well with the observed carcinogenic activity, and also, ${\pi}_{1.2.4}$ value increase with the metabolic activiting in agreement with the experimental facts that parent carcinogens activated with metabolism. Accordingly, we suggest that the 1, 2 and 4 positions in the carcinogenic compounds play the most important role in the process of chemical carcinogenesis, and also self-atom polarizability, as one of theoretical reactivity indices, is to be used as a measure of carcinogenic activity.

• 공업화학
• /
• 제1권2호
• /
• pp.232-239
• /
• 1990

${\gamma}$-Glycidoxy propyl trimethoxy slilane, CTBN rubber (carboxyl terminated butadiene acrylonitrile rubber), GMA(glycidyl methacrylate) 등을 TEA(triethylamine) 및 BPO(benzoyl peroxide) 존재하에 결정성 실리카의 표면에 단계적으로 반응시켜 2.5~5.8%(중량%)의 피복율을 가진 표면처리 실리카를 제조하였다. 이것을 전체혼합물 중 0~60%(중량%)가 되도록 에폭시 수지 및 MTHPA (methyltetrahydrophthalic anhydride)와 혼합한 후 경화시켜 굴곡특성 및 열적특성을 시험하였다. 시험결과, 충전재 함량 35~55%(중량%)에서, 실란/고무 또는 실란/고무/비닐로 처리된 실리카를 충전한 것은 에폭시 수지에 고무를 직접 3% 혼합하고 여기에 표면 처리하지 않은 실리카를 충전한 것에 비하여 굴곡강도와 Tg는 각각 평균 25%, 13% 높은 값을, 굴곡탄성율은 5% 낮은 값을 나타내었다.

• 멤브레인
• /
• 제19권4호
• /
• pp.310-316
• /
• 2009

조직 공학용 지지체로 사용할 목적으로 제조된 가교된 lactide/hyaluronic acid (LA/HA) 막의 분해 특성을 살펴보았다. 가교제 1,3-butadiene diepoxide (BD), 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)를 사용하여 얻어진 고분자 막을 $37^{\circ}C$로 조절된 항온조에서 증류수에 침전시켜 분해시켰다. 가교반응시 LA/HA 몰비가 작을수록, 가교제의 농도가 작을수록 생성된 고분자 막의 분해속도가 증가하였다. 분해될 때 막의 구조 변화를 살펴보기 위해 분해 전, 3일, 6일, 9일 후의 시료를 채취하여 핵자기 공명 분광법으로 분자 구조를 살펴보았다. EDC로 가교시킨 막의 경우 시간이 지남에 따라 HA-EDC 결합구조는 서서히 분해되는데 HA-LA 결합구조는 급격히 분해되어 6일 후에는 완전히 소멸되었다. BD로 가교시킨 막의 경우 가교된 결합 구조 모두 서서히 분해되었으며 3일, 6일이 지나면서 HA-BD 결합 구조는 원래의 89, 83%가 유지되었으나 HA-LA 결합 구조는 원래의 83, 65%로 유지되었다. 분해된 막을 전자 현미경으로 측정한 결과 분해 전후 표면에서 기공의 밀도는 크게 차이나지 않았으며, 표면과 측면의 구조도 크게 차이가 나지 않아 조직공학용 재료로써 사용할 때 아무런 문제가 없는 것으로 관찰되었다.

• Bulletin of the Korean Chemical Society
• /
• 제15권6호
• /
• pp.460-465
• /
• 1994

New silicon-monosubstituted (${\eta}^4$-2,3,4,5-tetraphenyl-l-silacyclopentadiene)transi tion metal complexes are described. (7-Alkyl-7-silanorbornadienyl)MLn(Alkyl=Methyl: MLn=CpRu$(CO)_2$: Alkyl=Methyl: MLn=CpNi(CO): Alkyl=Ethyl: MLn=CpNi(CO)) complexes were prepared from the corresponding silole-transition metal complexes with dimethylacetylenedicarboxylate. Cycloaddition products were obtained with 2,3-dimethyl-1,3-butadiene, 2,3-butanedione, and 1,4-benzoquinone through the ruthenium-substituted silylene. We have determined the crystal structure of (1-methyl-2,3,4,5-tetraphenyl-l-silacyclopentadien yl)cyclopentadienyldicarbonylruthenium by using graphite monochromated Mo-Ka radiation. The compound was crystallized in the monoclinic space group $P2_{1/c}$ with a = 9.838(l), b = 15.972(3), c = 18.327(3) ${\AA}$, and ${\beta}= 94.28(l)^{circ}$. The ruthenium moiety CpRu$(CO)_2$ on silicon is in an axial position.

• Elastomers and Composites
• /
• 제1권1호
• /
• pp.41-48
• /
• 1966

The physical properties of rubber coated fabrics, treated by means of spreading and topping process were studied. 1. The tearing strength of the rubber coated fabrics has shown decreasing tendency in comparison with fabric itself 2. Generally, the tearing strength is inversely proportional to the adhesion. 3. The value of hydrostatic pressure is in proportion to the density and tensile strength of the fabrics. 4. The topping process shows greater difference in adhesion initial and after water immersion than spreading process.

• Journal of Photoscience
• /
• 제10권2호
• /
• pp.181-184
• /
• 2003

Photochemical reactions of some organic molecules on titanium dioxide were investigated in methanol. A methanolic solution of trans-cinnamic acid and titanium dioxide was irradiated with 300 nm UV lamps for 24 h to afford methyl cinnamate. In the case of trans-cinnamamide, the major product was found to be 3-phenylpropionamide, i.e., a saturation product of ethylenic double bond. However, irradiation of urocanic acid, caffeic acid, ethyl cinnamate, trans-chalcone, trans-cinnamonitrile, trans-stilbene or trans, trans-1,4-diphenyl-1,3-butadiene on titanium dioxide under the same conditions did not give any noticeable products. Meanwhile, when irradiated some aromatic aldehydes, such as trans-cinnamaldehyde, l-naphthaldehyde, and 2-naphthaldehyde in methanol, vicinal diols and alcohols derived from the diols were produced. On the other hand, irradiation of 9-anthraldehyde and titanium dioxide in methanol afforded only alcohols, in which diol was not observed.

• Elastomers and Composites
• /
• 제51권3호
• /
• pp.233-239
• /
• 2016

Polyethylene (PE) and maleic anhydride-grafted PE (PE-g-MAH) were pyrolyzed, and their pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to investigate the influence of MAH grafted onto PE on pyrolysis behaviors. Major pyrolysis products of PE and PE-g-MAH were n-alkanes, 1-alkenes, ${\alpha},{\omega}$-alkadienes, and aromatic compounds. 1-Alkenes were more formed than n-alkanes, ${\alpha},{\omega}$-alkadienes, and aromatic compounds. Butadiene was more produced from PE than PE-g-MAH, whereas toluene and ethyl benzene were more generated from PE-g-MAH than PE. Difference in the pyrolysis behaviors between PE and PE-g-MAH were explained by initial decomposition of MAH moiety.

• Bulletin of the Korean Chemical Society
• /
• 제15권12호
• /
• pp.1103-1107
• /
• 1994

Interaction of triethylsilane and diphenylsilane ($Ph_2$$SiH_2$, $Ph_2$$SiD_2$) with the surfaces of rhodium has been examined by trapping the reaction intermediates with 2,3-dimethyl-l,3-butadiene. 1,4-Hydrosilylation of the diene is predominantly observed to occur under mild condition over the rhodium catalyst. It is inferred from the product analyses that silylene and silyl radicals bonded to rhodium surfaces are the intermediates for addition of silylene to the diene, and for 1,4-hydrosilylation, respectively.