• Macromolecular Research
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• 제16권7호
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• pp.614-619
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• 2008

Copolymers of phenyl alkyl acrylates/methacrylates are used clinically as soft materials for the foldable intraocular lens (IOL) to treat cataracts. In this study, copolymers of 2-phenylethyl acrylate (PEA) and 2-phenylethyl methacrylate (PEMA) of various compositions were prepared using free radical polymerization in solution. The composition of the copolymers was determined by $^1H$-NMR analysis. The reactivity ratios of the monomers were calculated using the conventional Fineman-Ross or Kelen-Tudos method. The reactivity ratio of PEA ($r_1$) and PEMA ($r_2$) were estimated to be 0.280 and 2.085 using the Kelen-Tudos method, respectively. These values suggest that PEMA is more reactive in copolymerization than PEA, and the copolymers will have a higher content of PEMA units. The glass transition temperature ($T_g$) of the copolymers increased with increasing PEMA content. The molecular weight and polydispersity indices ($M_w/M_n$) of the polymers were determined by GPC. Overall, these results are expected to be quite useful in applications to foldable soft IOL materials.

• Elastomers and Composites
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• 제50권3호
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• pp.189-195
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• 2015

In this study, we prepared epoxidized poly ethylene-ter-1-decene-ter-divinylbenzene (Epo-PEHV) as a reactive compatibilizer to prevent phase separation phenomenon which occurs upon blending polypropylene (PP) and ethylene-vinyl alcohol copolymer (EVOH). Firstly, PEHV was prepared under high catalyst activity according to content of catalyst and cocatalyst. After then, we modified vinyl group of the terpolymer with epoxy group. We observed that the terpolymer was successfully epoxidized by 1H-NMR and FT-IR analysis. The Epo-PEHV was added by 2, 5, 10% in PP/EVOH blends. The morphologies and mechanical properties of PP/Epo-PEHV/EVOH blends were analyzed by SEM and UTM, respectively. Epo-PEHV enhanced the interfacial adhesion of PP and EVOH blends.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1349-1354
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• 2013

Twenty two new 5-fluorouracil (5-FU) derivatives, 2-butoxy-4-substituted 5-fluoropyrimidines, were synthesized and characterized by IR, $^1H$ NMR, MS, HRMS. All compounds were preliminarily evaluated by MTT assay on human liver BEL-7402 cancer cell line in vitro. Ten compounds were selected to test their cytotoxic activity against A549, HL-60 and MCF-7 cancer cell lines in vitro. These compounds were more sensitive to BEL-7402 than other cell lines, particularly, cytotoxic activity of compounds 6b, 6d-f, 6p, 6s-u were in sub-micromolar scale. The highest cytotoxic potency against A549, HL-60 and MCF-7 was shown by 2-butoxy-4-chloro-5-fluoropyrimidine (5) with $IC_{50}$ values of 0.10, 1.66 and $0.59{\mu}M$, respectively. Compounds 6d and 6e were effective against MCF-7 with $IC_{50}$ $9.73{\mu}M$ and HL-60 with $IC_{50}$ $8.83{\mu}M$, respectively.

• Macromolecular Research
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• 제14권3호
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• pp.300-305
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• 2006

The chemical structure of a semi-aromatic polyimide-I, which was prepared by the chemical imidization of cyclopentanetetracarboxylic dianhydride and 2,2-bis(4-aminophenyl)hexafluoropropane, was characterized by $^{13}C-NMR$ spectroscopy. The chemically imidized polyimide-I was used for the preparation of a photosensitive polyimide (PSPI) through the addition of benzophenone and benzophenone oxime hexamethylene diurethane (BOHD), a photobase generator containing oxime-urethane groups. The polyimide-I film containing benzophenone and BOHD was not soluble in 2.38 wt% tetrabutylammonium hydroxide solution in $H_2O$. However, it became soluble following irradiation with 310 nm UV light. A positive tone image with a resolution of $5{\mu}m$ was obtained with this PSPI, having sensitivity($D_c$) of $1.2J/cm^2$ and contrast(${\gamma}_p$) of 1.08. Thus, a polyimide, which is not intrinsically photosensitive, can become photosensitive through the addition of a photobase generator containing oxime-urethane groups as a photosensitive compound.

• 한국염색가공학회지
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• 제17권6호
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• pp.1-10
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• 2005

Disperse dyes derived from heterocyclic compounds such as phenylindole, pyridone, diaminopyridine, and carbazole have been known to exhibit high light fastness and bathochromic shift compared to the coursponding aminoazobenzene. The synthetic method to obtain diaminopyridine derivatives, which can be used as coupling components, was chlorination of pyridone with phosphorous oxychloride, followed by substitution with various primary amines. Four azo disperse dyes were synthesized by coupling four diaminopyridines with 2-cyano-4-nitroaniline as a diazo component. Structures of these dyes were confirmed by $^1H$ NMR spectroscopy. The wavelengths of maximum absorption of the synthesized disperse dyes were in the range of $517\~528nm$, and molar extinction coefficients were $45,700\~50,100$. The dyeability of four disperse dyes toward PET fiber was generally good. Wash and rubbing fastnesses were excellent, while light and dry heat fastness were good.

• Journal of Dairy Science and Biotechnology
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• 제21권2호
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• pp.138-147
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• 2003

We here analyzed and proposed the structures of the N-linked sugar chains of PAS-7 from bovine milk fat globule membrane. The N-linked sugar chains were liberated from PAS-7 by hydrazinolysis and, after modifying the reducing ends with 2-aminopyridine (PA), were separated into one neutral (7N,55%) and two acidic (7M mono-, 43%; 7D, di-, 2%) sugar chain roups. The latter were converted into neutral groups (7MN and 7DN) by sialidase digestion. The structure of each of these PA-neutral sugar chains was determined by sugar analysis, sequential exoglycosidase digestion, partial acetolysis, and 1H-NMR spectroscopy. The results show that the 10 sugar chains were of the biantennary complex type with and without fucose. The structure of 7N2A one of the major sugar chains, was proposed as; [structure: see text] A structural comparison between PAS-6 and -7 indicated that although they shared the same protein core, their sugar moiety was markedly different, involving the existence of a different pathway during the post-transcriptional modification.

• 한국자기공명학회논문지
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• 제1권1호
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• pp.7-20
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• 1997

The mapping of the spin-spin relaxation time T2 in pixed-by-pixel was suggested as a quantitative diagnostic tool in medicine. Although the CPMG pulse sequence has been known to be the best pulse sequence for T2 measurement in physics NMR, the supplied pulse sequence by the manufacture of MRI system was able to obtain the maximum of 4 CPMG images. Eight or more images with different echo time TEs are required to construct a reliable T2 map, so that two or more acquisitions were required, which easily took more than 10 minutes. 4-echo CPMG imaging pulse sequence was modified to generate the maximum of 8 MR images with evenly spaced echo time TEs. In human MR imaging, since patients tend to move at least several pixels between the different acquisitions, 8-echo CPMG imaging sequence reduces the acquisition time and may remove any misregistration of each pixel's signal for the fitting T2. The resultant T2 maps using the theoretically simulated images and using the MR images of the human brain suggested that 8 echo CPMG sequence with short echo spacing such as 17∼20 msec can give the reliable T2 map.

• Bulletin of the Korean Chemical Society
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• 제21권1호
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• pp.110-117
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• 2000

A series of new liquid crystalline dimesogenic compounds with chiral tails was synthesized, and their thermal and liquid crystalline properties were studied. The chain length of the central polymethylene spacers (x) was varied from dimethylene (2) to decamethylene (12). These compounds were characterized by elemental analysis, IR and NMR spectroscopy, differential scanning calorimetry (DSC), and cross-polarizing microscopy. All compounds were found to be enantiotropically liquid crystalline, and the values of melting ($T_m$) and isotropization temperature ($T_i$) as well as enthalpy change (Δ$H_i$) and entropy change for isotropization (Δ$S_i$) decreased in a zig-zag fashion revealing the so-called odd-even effect as x increases. Their mesomorphic properties fall into three categories depending upon x; (a) compounds with x=2 and 4 formed two different mesophases, smectic and cholesteric phases in that order on heating, and vice versa on cooling, (b) compounds with x=3, 7, 8, 10 and 11 reversibly formed only the cholesteric phase, and (c) compounds with x=5, 6, 9 and 12 exhibited only a cholesteric phase on heating, whereas on cooling they formed two different mesophases, cholesteric and smectic phases, sequentially.

• Bulletin of the Korean Chemical Society
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• 제15권7호
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• pp.553-559
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• 1994

Dynamics of $CH_2CI$ group in ${\alpha},2,6$-trichlorotoluene dissolved in $CDCl_3$ was studied by observing various relaxation modes for $^{13}C$ under proton undecoupled condition. Partially relaxed $^{13}C$ spectra were obtained at $34^{\circ}C$ as a function of evolution time after applying various designed pulse sequences to this $AX_2$ spin system. It was found that nonlinear regression analysis of the relaxation data for these magnetization modes could provide the information about dipolar and spin-rotational auto-correlation and cross-correlation spectral densities for fluctuation of the $^{13}C-^1H$ internuclear vector in $CH_2Cl$ group. The results show that the effect of cross-correlation is comparable in magnitude to that of auto-correlation and the relaxation in this spin system is dominated by dipolar mechanism rather than spin-rotational one. From the resulting spectral density data we could calculate the bond angle ${\angle}HCH\;(105.1$^{\circ}$) and elements of the rotational diffusion tensor for $CH_2Cl$ group.

• 대한화장품학회지
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• 제28권1호
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• pp.116-134
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• 2002

세리신은 누에고치의 고치실에서 추출되는 천연 단백질로서 많은 수산화기를 가지고 있어 뛰어난 보습성을 가진다. 이에 화장품에의 응용이 기대되나, 물에 잘 녹지 않는 특성을 가지고 있어서 화장품 원료로 사용하기에 어렵다는 단점이 있다. 본 연구에서는 친양쪽성 화합물인 poly(ethylene glycol)(PEG)을 세리신에 도입하여 수용성이며 자기조합형(self-assembled) 세리신-PEG 결합체를 합성하였다. 세리신내의 tyrosine 잔기의 방향 족 수산화기가 반응사이트임을 $^1$H-NMR 분석으로 알 수 있었으며, IR과 CD 측정으로 PEG 사슬의 도입으로 세리신의 구조가 불규칙한 coil구조에서 $\beta$-sheet구조로 구조적 변화가 일어남을 알 수 있었다. 또한 DSC 분석에서 세리신-PEG결합이후 각각의 녹는점이 떨어지는 것을 확인하여 상호 결정성에 영향을 주는 것을 확인하였다. 세리신-PEG 결합체는 자기조합하여 소수성 상호작용을 통해 200-400nm의 구형 나노입자를 이루며 투석방법을 통하여 얻을 수 있었다. 또한, 세리신-PEG 나노입자는 세리신자체보다 더 높은 보습력을 가지는 것을 확인하였다. 세리신-PEG 결합체의 cytotoxicity는 MTT assay에 의해 독성이 없음을 확인하였으며, 동물실험에 의한 독성도 전혀 나타내지 않음을 알 수있었다. 나노입자의 특성과 세리신의 보습성, 세리신-PEG의 친양쪽성 특성으로 세리신-PEG결합체 나노입자는 그 자체로도 원료로 사용 될 수 있을 뿐 아니라 생리 활성성분의 운반체로의 개발이 기대되어 진다.