• 공업화학
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• 제9권2호
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• pp.185-192
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• 1998

네 종류의 폴리아믹산(PPA)은 서로 다른 구조의 디아민들인 3,3'-diaminodiphenyl sulfone(3,3'-$DDSO_2$), 4,4'-diarrinodiphenyl sulfone(4,4'-$DDSO_2$), 4,4'-methylene dianiline(4,4'-MDA) 및 4,4'-oxydianiline(4,4'-ODA)와 디안하이드라이드인 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA)를 용매인 DMAc를 이용하여 합성되었다. 이들의 폴리아믹산(PAA)을 이용하여 poly[2,2-(m-phenylene)-5,5'-bibenzimidazole](PBI)와 용액 블렌딩하여 Blend-I, II, III, 그리고 IV로 칭하였으며, 이에 대한 시료를 필름이나 분말로 제조한 PBI/PAA 시스템을 예상된 $T_g$보다 높은 온도에서 열경화시켜 PBI/PI 블렌드로 전환시킨후 PI 합성시 사용된 디아민의 분자구조 변화에 따른 블렌드의 상용성과 그 상호작용의 상대적인 세기를 살폈다. 이로부터 본 연구에서 이용된 네 개의 블렌드들은 상용성을 보였으며, 이들 상용성을 가져다주는 상호작용의 세기는 Blend-III와 Blend-IV가 Blend-I와 Blend-II보다 큼을 보였다. 이와 같이 블렌드에 사용된 PI의 구조변화에 따라 상호작용이 다른 것은 PI합성시에 사용된 디아민의 구조에서 페닐링 사이에 존재하는 linkage인 O나 $CH_2$보다는 $SO_2$가 존재할 때 블렌드를 이루는 두 고분자사이의 상호작용인 수소결합력을 약화시키는 spacer로 작용하였다고 판단된다.

• 공업화학
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• 제9권2호
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• pp.207-213
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• 1998

전편의 연구결과[1]를 토대로 또 다른 방법으로써 폴리이미드의 구조를 변화시켜 방향족 폴리벤즈이미다졸(PBI)과의 블렌드들의 상용성 및 상용성을 가져다 주는 상호작용의 세기를 상대적으로 비교하였다. 이 연구에서 방향족 폴리이미드(PI)는 두 개의 디아민인 4,4'-methylene dianiline (4,4'-MDA)과 4,4'-oxydianiline (4,4'-ODA)을 dianhydride인 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA)와의 축합반응을 통하여 용매인 DMAc로 폴리아믹산(PAA)을 합성한 후 열경화하여 얻었다. 이들 폴리아믹산(PAA)을 poly2,2-(m-phenylene)-5,5'-bibenzimidazole (PBI)와 용액 블렌딩하여 PBI/PAA 블렌드를 열경화시켜 PBI/PI의 블렌드로 전환시킨후 상용성을 조사하고 전편의 블렌드에 사용된 폴리이미드[1]와 이 연구에 사용된 폴리이미드의 구조변화에 대한 상호작용의 상대적인 크기를 조사하였다. 연구에 사용된 두 가지 블렌드인 PBI/DSDA+4.4'-MDA (Blend-V)와 PBI/DSDA+4.4'-ODA (Blend-VI)는 사용성을 보였다. 이는 성현된 필름이 투명하고, 전 블렌드 조성에 대해서 하나의 $T_g$를 가지며, 또한 블렌드 조성에 따른 N-H ($3418cm^{-1}$)와 C=O 스트레칭 밴드(1730 및 $1780cm^{-1}$)의 주파수 이동폭이 각각 $39{\sim}40cm^{-1}$, $5{\sim}6cm^{-1}$와 $3{\sim}4cm^{-1}$이었다. 이 연구에 사용된 블렌드들에 대하여 두 성분 고분자간 상호작용의 세기를 실험치와 Fox식으로 계산된 유리전이온도차로 생긴 면적(A), Gordon-Taylor 식에서의 ${\kappa}$ 값, 그리고 관능기인 N-H와 카보닐기의 주파수 이동폭의 변화로 살펴보았다. 이들에 대한 결과로 먼저, 면적 (A)와 ${\kappa}$ 값에 있어서 Blend-V와 Blend-VI이 전편의 블렌드 [1]인 Blend-III와 Blend-IV에 비해 작은 값을 보였다. 또한 관능기의 주파수 이동에 있어서도 이에 대한 결과와 유사한 결과를 보였다. 따라서 블렌드에 사용된 PI의 구조변화에 따라 상호작용이 다른 것은 PI 합성시에 사용된 서로 다른 dianhydride의 구조에서 페닐링 사이에 존재하는 linkage인 C=O보다 $SO_2$가 존재할 때[Fig. 2] 블렌드를 이루는 두 고분자사이의 상호작용인 수소결합력을 약화시키는 spacer로 작용한 것으로 사료된다. 다시 말하면, 전자가 후자보다 더 큰 입체장애를 일으켰기 때문이라 사려된다.

• 폴리머
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• 제25권5호
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• pp.671-678
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• 2001

Sodium 또는 zinc로 중화된 poly(ethylene-co-methacrylic acid)의 아이오노머는 ethylene 사슬 부분들로만 이루어진 결정상, acid 그룹이 존재하는 amorphous 영역, 그리고 ionic aggregate의 세 가지 상으로 나누어진다. Soaking에 의하여 흡수된 nonionic dye 분자들은 결정상을 제외한 amorphous 부분이나 ionic aggregate 분근에 존재하는데, 주위 사슬의 극성에 따라 dispersion force (ethylene 사슬 부분), polar force (acid 부분), ionic dipole (ionic aggregate 부분)의 세 가지 다른 힘의 영향 아래 놓이게 된다. 극성이 적은 ethylene 사슬부분의 dispersion force 영향 아래에 존재하는 Nile Red의 UV/Vis 흡수피크는 500nm 부근에서, polar한 acid 그룹의 영향을 받는 dye 피크는 525 nm, 그리고 ionic aggregate의 영향에 의한 dye는 Na+-아이오노머의 경우 550 nm, divalent이어서 더 큰 ionic dipole을 가지는 $Zn^{2+}$-아이오노머의 경우 610nm에서 각각 피크가 나타났다.

• 폴리머
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• 제27권2호
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• pp.91-97
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• 2003

각기 다른 온도에서 불소화 표면처리에 의한 실리카의 표면특성을 X-선 광전 분광법 그리고 접촉각을 통해 관찰하였으며, 복합재료의 기계적 계면물성과 열안정성에 미치는 영향은 인열 에너지와 분해 활성화 에너지를 통해 고찰하였다. 실리카 표면 자유 에너지의 London 비극성 요소와 불소작용기는 불소화 처리 온도에 따라 증가하였으며, 결과적으로 실리카/폴리우레탄 복합재료의 인열 에너지를 향상시켰다. 또한 복합재료의 열안정성은 불소화 함량에 따라 증가하였다. 이러한 결과는 실리카 표면에 도입된 불소작용기가 본 실험의 복합재료 시스템 내에서 실리카와 폴리우레탄 계면 사이의 분자간 상호작용을 향상시키는 주요한 인자로 작용한 것으로 사료된다.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.520-529
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• 2017

Viscosity data were measured at 298.15 K and 308.15 K for formamide + 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol or 2-methyl-2-propanol mixtures. For an equimolar mixture, deviation in viscosity follows the sequence: 2-methyl-2-propanol >2-methyl-1-propanol>1-butanol>2-propanol>1-propanol. The viscosity data were further analyzed in terms of graph theory. Free energy of activation was also calculated from experimental viscosity data along with previously reported excess volume data. The deviation in viscosity and free energy of activation were fitted to Redlich-Kister polynomial equation. The viscosity data were also correlated by correlations like Grunberg-Nissan, Tamura-Kurata, HindMcLaughlin-Ubbelohde, and Katti-Chaudhari relation. Various adjustable parameters, $G_{12}$, $T_{12}$, $H_{12}$, and $W_{vis}/RT$, of various correlations were used to predict viscosity deviation of binary mixtures. Positive value of $G_{12}$ indicates strong interaction in the studied systems. Grunberg-Nissan relation has lowest deviation among the four correlations for formamide + 1-propanol or 2-propanol mixtures; and for mixtures of formamide with 1-butanol or 2-methyl-1-propanol, TamuraKurata has lowest deviation. Grunberg-Nissan gives lowest deviation for formamide + 2-methyl-2-propanol mixtures.

• 통합자연과학논문집
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• 제3권4호
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• pp.226-230
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• 2010

Calculation of partial charge is important in chemistry. However, because there are many methods developed, it is of considerable interest to know how to calculate and apply properly to address various chemical problems. For basis set, usually double zeta quality is acceptable, and double zeta polarization function would be enough for most cases. To describe electronic state more accurately, Many electron configurations would be necessary to describe highly strained or anionic species. The NPA population introduced new concept about amide bonds, i.e., the planar geometry of nitrogen atom may not come from resonance, but from the lowering of p-orbital energy by electronegative carbonyl carbon atom. The issues for hypervalent atomic charges was also addressed by various charge derivation scheme. When the charge schemes were applied to organolithium compounds, the ionic nature of boding was revealed. This comes from the fact that previous Mulliken partial atomic charges overemphasized the covalent character, wihout much justification. The other partial charge derivation schemes such as NPA(natural population analysis), IPP (Integrated Projected Population) showed that much more ionic picture. ESP potential derived charges are generally believed to be suitable to describe intermolecular interactions, therefore they are used for molecular dynamics simulations and CoMFA (comparative molecular field analysis). The charge derivation schemes using multipole polarization was mainly applied to reproduce experimental infrared spectroscopy. In some reports these schemes are also suitable for intermecular electrostatic interactions. Charges derived from electron density gradient have shown the some bonds are not straight, but actually bent. The proper choice of charge-calculation method along with suitable level of theory and basis set are briefly discussed.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1951-1955
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• 2010

A new blue light emitting anthracene derivative, 9,10-bis-(9',9'-diethyl-7'-t-butyl-fluoren-2'-yl)anthracene (BETF), has been designed and synthesized by a palladium catalyzed Suzuki cross-coupling. A theoretical calculation of the three-dimensional structure of BETF supports that it has a non coplanar structure and inhibited intermolecular interactions resulting in high luminescent efficiency and high color purity. BETF has good thermal stability with glass-transition temperature (Tg) of $131^{\circ}C$. The PL maximum of BETF in solution and film were 438 nm and 440 nm, respectively, showing pure blue emission. A multilayer device using BETF as emitting material exhibits maximum luminescence efficiency of 2.2 cd/A and a pure blue emission (Commission Internationale de L'Eclairage (CIE) coordinates of x = 0.15, y = 0.10).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.126-126
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• 2016

Understanding adsorption behavior organic molecules at oxide surfaces is very important for the application of organic-inorganic hybrid materials. Recently, monoethanolamine (MEA) adsorbed on $TiO_2$ surface has received great interests because it can lower the work function of $TiO_2$ in photo-electronic devices such as OLED and solar cells. In this study, we investigated the role of surface defects in adsorption behaviors of MEA at the rutile $TiO_2$ (110) surface by combined study of scanning tunneling microscopy and density functional theory calculations. Our results revealed that oxygen vacancy is the most stable adsorption site for MEA on $TiO_2$ (110) surface at low coverage. As coverage increases, the oxygen vacancies are occupied with the molecules and MEA molecules start to adsorb at Ti rows at higher coverages. Our results show that the defects at oxide surfaces and the intermolecular interactions are important factors for determining stable adsorption structure of MEA at $TiO_2$ (110) surfaces.

• Korea-Australia Rheology Journal
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• 제15권1호
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• pp.1-7
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• 2003

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly (sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhances desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 ${\AA}$ and 24 ${\AA}$, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with well-defined micropatterns in a short process time is Introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by the .spinning process.

• 한국환경과학회지
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• 제12권8호
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• pp.871-879
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• 2003

The complexation of co-contaminant mixtures between Ag(I) and polycyclic aromatic hydrocarbon (PAH) molecules (naphthalene, pyrene, and perylene) were investigated to quantify the equilibrium constants of their complexes and elucidate the interactions between Ag(I) and PAH molecules. The apparent solubilities of PAHs in aqueous solutions increased with increasing Ag(I) ion concentration. The values, K$_1$ and K$_2$ of equilibrium constants of complexes of Ag(I)-PAHs, were 2.990 and 0.378, 3.615 and 1.261, and 4.034 and 1.255, for naphthalene, pyrene, and perylene, respectively, The K$_1$and K$_2$ values of PAHs for Ag(I) increased in the order of naphthalene ＜ pyrene ＜ perylene and naphthalene ＜ pyrene ≒ perylene, respectively, indicating that a larger size of PAH molecule is likely to have more a richer concentration of electrons on the plane surfaces which can lead to stronger complexes with the Ag(I) ion. For the species of Ag(I)-PAH complexes, a 1:1 Ag(I) : the aromatic complex, AgAr$\^$＋/, was found to be a predominant species over a 2:1 Ag(I) : aromatic complex, Ag$_2$Ar$\^$＋＋/. The PAH molecules with four or more aromatic rings and/or bay regions were observed to have slightly less affinity with the Ag(I) ion than expected, which might result from inhibiting forces such as the spread of aromatic $\pi$ electrons over o wide molecular surface area and the intermolecular electronic repulsion in bay regions.