• 한국응용과학기술학회지
• /
• 제27권2호
• /
• pp.129-136
• /
• 2010

A series of noble poly(amide-imide)s and copoly(amide-imide)s bearing 1,2-bis(4-phenoxy)benzene units were synthesized by the direct polycondensation of 1,2-bis(4-trimellitimidophenoxy)benzene[1,2-PTPB] with a combination of commercially available aromatic diamines and diacids such as m-phenylene diamine, p-phenylene diamine(PPD), isophthalic acid and terephthalic acid(TA) in N-methyl-2-pyrrolidone(NMP) using triphenyl phosphite and pyridine as a condensing agent in the presence of dehydrating agent ($CaCl_2$). The resulting polymers had inherent viscosities in the range of 0.37~0.78 dL/g and most of them were soluble m common organic solvents including NMP, dimethylacetamide, dimethylsulfoxide, dimethylformamide, and m-cresol. Wide-angle X-ray diffractograms revealed that the copoly(amide-imide) derived from PPD with mixed acids of 1,2-BTPB and TA, showed crystalline nature, whereas all of the other polymers were found to be amorphous. The glass transition temperatures of the polymers occurred over the temperature range of $270{\sim}323^{\circ}C$ in their differential scanning calorimetry curves and their 10% weight loss temperature, determined by thermogravimetric analysis in air and nitrogen atmosphere, were in the range $465{\sim}535^{\circ}C$, $500{\sim}550^{\circ}C$, respectively, indicating their good thermal stability.

• Bulletin of the Korean Chemical Society
• /
• 제24권9호
• /
• pp.1276-1280
• /
• 2003

Thermal behavior of bromphenols was investigated by direct pyrolysis at high temperature. The thermal degradation products formed by the pyrolysis of mono-bromophenols (o-, m-, and p-) were identified by gas chromatography-mass spectrometry. During the pyrolysis reactions, several kinds of dioxins and furans were produced, and the relative ratio of pyro-products was dependent on the substituted position of bromine in phenolic structure due to the effect of symmetry and steric hindrance. The formation of dioxins can be explained by the phenoxy radical addition and Br atom elimination at an ortho-carbon site on phenolic structure. On the other hand, the formation of furans can be explained by the ortho-ortho carbon coupling of phenoxy radicals at unsubstituted sites to form o, o'-dihydroxydiphenyl intermediate via its keto-tautomer, followed by $H_2O$ elimination. The pyrolysis temperature has also a substantial effect on the dimerized products quantities but little effect on the type of pyro-products. Moreover, the formation mechanism of pyro-products was suggested on the basis of products identified.

• Advances in nano research
• /
• 제14권4호
• /
• pp.355-362
• /
• 2023

Physical exercise, especially intense exercise and high intensity interval training (HIIT) by trampoline, can lead to muscle injuries. These effects can be reduced with intelligent products made of nanocomposite materials. Most of these nanocomposites are polymers reinforced with silicon dioxide, alumina, and titanium dioxide nanoparticles. This study presents a polymer nanocomposite reinforced with silica. As a result of the rapid reaction between tetraethyl orthosilicate and ammonia in the presence of citric acid and other agents, silica nanostructures were synthesized. By substituting bis (4-amino phenoxy) phenyl-triptycene in N, N-dimethylformamide with potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C, the diamine monomer bis (4-amino phenoxy) phenyl-triptycene is prepared. We synthesized a new polyaromatic (imide) with triptycene unit by sol-gel method from aromatic diamines and dianhydride using pyridine as a condensation reagent in NMP. PI readily dissolves in solvents and forms robust and tough polymer films in situ. The FTIR and NMR techniques were used to determine the effects of SiO₂ on the sol-gel process and the structure of the synthesized nanocomposites. By using a simultaneous thermal analysis (DTA-TG) method, the appropriate thermal operation temperature was also determined. Through SEM analysis, the structure, shape, size, and specific surface area of pores were determined. Analysis of XRD results is used to determine how SiO₂ affects the crystallization of phases and the activation energy of crystallization.

• 폴리머
• /
• 제36권6호
• /
• pp.776-788
• /
• 2012

셀로비오스, 말토오스 그리고 락토오스를 1-{4-(4'-시아노페닐아조)펜옥시}옥틸브롬 혹은 1-{4-(4'-시아노페닐아조)펜옥시카보닐}헵타노일 클로라이드와 반응시켜 옥타[8-{4-(4'-시아노페닐아조)펜옥시}]옥틸 그리고 옥타[8-{4-(4'-시아노페닐아조)펜옥시카보닐}]헵타노화 이당류 유도체들을 합성함과 동시에 이들의 열방성 액정과 광화학적 상전이 거동을 검토하였다. 모든 {(시아노페닐아조)펜옥시}옥틸 이당류 에테르들(CADETs)은 단방성 네마틱(N) 상들을 형성하는 반면 모든 {(시아노페닐아조)펜옥시카보닐}헵타노화 이당류 에스터들(CADESs)은 양방성 N 상들을 형성하였다. CADETs에 비해, CADESs는 높은 액체(I) 상에서 N 상으로의 전이 온도들을 나타냈다. 유리 셀 혹은 러빙된 폴리이미드(PI) 배향막을 지닌 셀 중에서 N 상을 형성하고 있는 이당류 유도체에 광을 조사시킬 경우, 아조벤젠기의 trans-cis 이성화에 의해 N 상은 I 상으로 변하였다. 한편, 광 조사시켜 얻은 시료를 광을 차단한 상태로 방치할 경우 열에 의한 cis-trans 이성화와 trans 아조벤젠기들의 재배열로 인하여 I 상은 최초의 N 상으로 변하였다. 유리 셀의 경우에 비해 러빙된 PI 배향막을 지닌 셀의 경우가 이당류 유도체들의 광화학적 N-I 그리고 열적 I-N 상전이 속도들은 빠르며 시아노아조벤젠기를 지닌 monomesogenic 화합물들 그리고 4-{4'-(시아노페닐아조)펜옥시}옥틸 글루코오스 그리고 셀룰로오스 에테르들에 대해 관찰되는 결과들에 비해 현저히 달랐다. 이러한 결과를 주사슬의 유연성, 반복단위당에 도입된 메소겐기들의 수 그리고 아조벤젠기들간의 거리에 기인한 아조벤젠기들의 협동효과의 차이의 견지에서 검토하였다.

• 농약과학회지
• /
• 제3권3호
• /
• pp.11-19
• /
• 1999

Fenoxaprop-ethyl계 화합물의 amide 형태로 합성된 기질로써 일련의 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpropionamide 유도체들은 건답에서 발아 후 (post), 벼와 피 (Echinochloa crus-galli)에 대하여 Fenoxaprop-ethyl 보다 비교적 양호한 선택성을 나타내었으며 N-phenyl 치환체들의 선택성에 관한 구조-활성과의 관계 (SAR)를 Free-Wilson 방법과 Hansch 방법을 이용하여 정량적으로 검토하였다. 피의 제초활성에는 N-phenyl 고리상 meta-치환된 1 치환체들과 ortho, meta, para-치환된 3 치환체로서 methyl 및 methoxy 등의 치환체들이 비교적 높게 기여하였다. 또한 적정값 ($({\pi})_{opt.}=1.60$)의 소수성을 갖는 전자 밀게 (${\sigma}<0$)들의 공명효과 (R<0)가 제초활성을 개선하는데 영향을 미치고 있음을 알았다. 벼의 경우에는 para-치환된 1-치환체나 ortho, para-치환된 2-치환체로써 Taft의 입체효과 (Es)에 대한 적정값 ($(ES)_{opt.}=0.87$)을 벗어나는 전자 밀게에 의한 공명효과 (R<0)가 약해를 줄이기 위한 조건이었으며 벼와 피 사이의 선택성에 기여하는 물리-화학적인 요인이었다. 그리고 SAR식에 따라 온실 내에서 피에 대하여 가장 큰 활성을 나타내는 화합물은 2-ethoxy-3-methoxy-4-dimethylamino 치환체 ($pI_{50}$=6.60, 1g/ha)로 예상되었다.

• 한국환경성돌연변이발암원학회:학술대회논문집
• /
• 한국환경성돌연변이발암원학회 2002년도 Molecular and Cellular Response to Toxic Substances
• /
• pp.170-170
• /
• 2002

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.159-160
• /
• 2006

We developed novel catalyst, PHENICS composed of the combination of a cyclopentadienyl group to perform a high catalytic activity and a bulky phenoxy group, which performs the production of high molecular weight polyolefin. The polymerization activity of PHENICS at high temperature is higher than well-known CGC catalyst. PHENICS showed the excellent ability of comonomer incorporation into polymer chain. The obtained copolymer had a high molecular weight. The PHENICS catalyst is also active to the copolymerization of ethylene and several vinyl comonomers such as styrene, norbornen, and conjugated dienes. We will discuss new cocatalysts for PHENICS to improve activity and the ability of molecular weight control.

• 생약학회지
• /
• 제28권3호
• /
• pp.143-148
• /
• 1997

From the root of Symplocarpus renifolius, four compounds were isolated and their structure was elucidated by chemical and spectroscopic methods. They were identified as ${\beta}-sitosterol$ (compound 1), asparagine (compound 2), isocorydine (compound 3) and 3-hydroxymethyl-4-phenyl phenoxy carboxylic acid glucopyranosyl ester (compound 4). These compounds were firstly isolated from roots of Symplocarpus renifolius. Compound 4 was identified as a new compound, named as symplocarposide.

• 한국독성학회:학술대회논문집
• /
• 한국독성학회 2003년도 추계학술대회
• /
• pp.165-165
• /
• 2003

Phenxoy compounds, 2,4-dichlorophenol acetoxyacid (2,4-D) and 2,4-dichlorophenol (DCP), are widely used as a hormonal herbicide and intermediate for pesticide manufacturing, respectively. We have previously reported the potential of these compounds as androgenic endocrine disruptors using in vivo Hershberger assay and in vitro reporter gene assay.(omitted)

• 대한화학회지
• /
• 제42권3호
• /
• pp.315-322
• /
• 1998

새로운 에메소겐 액정화합물들을 합성하였고, 이들의 열적 및 액정 성질을 DSC와 가열판이 부착된 편광현미경을 사용하여 조사하였다. 이 화합물들 즉, 1,10-bis[2,5-bis(4-substitutedphenoxycarbonyl)phenoxy]decane은 "H-자형" 이합체 대칭화합물의 구조로 중앙의 테페프탈로일 단위에 oxydecamethyleneoxy 격자를 통하여 상호 연결된 두 개의 bis(p-substitutedphenoxy)terephthalate 단위로 이루어졌다. 메소겐의 치환기는 X=-F, -H, -I, -Cl, -Br, $-NO_2,\;-CF_3,\;-OC_4H_9-CN$ 및 $-C_6H_5$를 바꾸어 보았다. $X=-OC_4H_9-CN$과 $C_6H_5$ 화합물은 단방성 네마틱액정이었으며 이에 비하여 X=-F, -H, -I, -Cl, -Br, $-NO_2$와 $-CH_3$는 액정이 아니었다. 이 화합물들의 네마틱 그룹 효율은 $-C_6H_5>-CN>-OC_4H_9$ 순이었다.