• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.236-236
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• 2006

Time-resolved photoluminescence spectroscopy measurements of oligofluorenes with various side chains were studied. With extremely pure oligofluorenes, two kinds of red-shifted green emission were observed which have different origins; aggregate formation and on-chain chemical defect. The green emission around 490 nm was largely dependent upon the intermolecular interaction of oliglfuorene molecules. Moreover, by using oligofluorene with high-order liquid crystalline phase, we observed that the green emission was strongly dependent upon the molecular packing in solid films.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.229-229
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• 2006

Recently there has been significant interest in utilizing functional semiconductor polymers for electronic and opto-electronic devices such as Light-emitting diodes, thin film field effect transistors, solar cells, displays, and chemical and biosensors. However, better materials and further understanding of their electronic properties are critical for devices based on these materials. In this work, we use various scanning probe techniques, spectroscopy, and device fabrication to study the molecular interactions, optical and charge transport properties in conjugated polyelectrolytes. Using chemical synthesis approach, we are able to tune the molecular packing and interactions in these materials, which in turn, influence their electronic properties and device performance.

• Polymer(Korea)
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• v.38 no.4
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• pp.464-470
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• 2014

A chemo-mechanical method was used to prepare lignin-containing cellulose nanofibrils(L-CNF) from unbleached woodpulps dispersed uniformly in an organic solvent. L-CNF/PLA composites were obtained by solvent casting method. The effects of L-CNF concentration on the composite performances were characterized by tensile test machine, contact angle machine, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The tensile test results indicated that the tensile strength and elongation-at-break increased by 50.6% and 31.8% compared with pure PLA. The contact angle of PLA composites decreased from $79.3^{\circ}$ to $68.9^{\circ}$. The FTIR analysis successfully showed that L-CNF had formed intermolecular hydrogen bonding with PLA matrix.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2471-2476
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• 2007

A series of titanium complexes containing terdentate β-ketoiminate ligands were found to be efficient for the ring-opening polymerization of ε-caprolactone (ε-CL), producing poly(ε-caprolactone) (PCL) with bimodal distribution. Steric factors imposed by methyl substituents on the back bone of the alkoxy group affected significantly the polymerization rate and physical properties of the resulting PCL. Intra- and intermolecular transesterifications rather than disproportional rearrangements were responsible for the bimodal behavior and for the change in the molecular weight (Mw). Dilution with toluene reduced yield, and lowered polydispersity (PDI) and Mw of PCL, while the catalytic activities of the dimeric complex, [Ti(Oi-Pr)2(N-alkoxy-β- ketoiminate)]2 and Ti(Oi-Pr)4 were not sensitive to the added solvent. The dimeric complex showed living character, while other catalysts suffered from chain termination reactions.

• Journal of Information Display
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• v.11 no.4
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• pp.144-148
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• 2010

In this paper, vertically aligned (VA) liquid crystal (LC) modes were investigated using the alkyl chain ordering effect of self-assembled monolayers (SAMs) prepared on the anisotropic inorganic surface. On the anisotropic surface prepared through oblique ion beam irradiations, the SAM molecules are adsorbed, producing macroscopic alkyl chain ordering, which can determine the pretilt direction of the vertically aligned LC molecules through the intermolecular interactions on the surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1088-1091
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• 2003

We have studied liquid crystal orientation on rubbed and photoaligned polymer surfaces. The following topics will be presented; (1) visualization of nonuniformity of rubbing, (2) competition between grooves and photoalignment and (3) alignment process of 5CB evaporated on treated surfaces. Through these topics, the importance of the intermolecular liquid crystalline interaction will be emphasized.

• Coupled systems mechanics
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• v.6 no.3
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• pp.369-376
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• 2017

Intermolecular interaction energies and conformer geometries of the hydrogen bonded acrylamide dimers have been studied by using the second-order Møller-Plesset (MP2) perturbation theory and the density functional theory (DFT) with 17 density functionals. Dunning's correlation consistent basis sets (up to aug-cc-pVTZ) have been used to study the basis set effects. The DFT calculated interaction energies are compared to the reference energy data calculated by the MP2 method and the coupled cluster method at the complete basis set (CCSD(T)/CBS) limit in order to determine the relative performance of the studied density functionals. Overall, dispersion-energy-corrected density functionals outperform uncorrected ones. The ${\omega}B97XD$ density functional is particularly effective in terms of both accuracy and computational cost in estimating the reference energy values using small basis sets and is highly recommended for similar calculations for larger systems.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1E
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• pp.24-28
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• 1997

Ultrasonic relaxation measurements for imidazole and its derivative in phosphate buffer exhibit a high peak of absorption at neutral pH. Near neutral pH, protolysis and hydrosis may be neglected and the essential reaction only consists of a direct proton-exchange. The kinetics constants and the volume changes for the proton transfer reaction with the protonated imidazole and 2-methylimidazole have been determined at 25℃. The kinetics constants are 7.2×108s-1M-1for imidazole and 1.7×108s-1M-1 for 2-methylimidazole. The kinetics constants are used to estimate the spectrum of relaxation times and acoustic relaxation amplitude associated with intermolecular and intramolecular proton-exchange reactions in bilogical media. It is concluded that the magnitude of the acoustic absorption reasonalbly attributable to the perturbation of proton-transfer equilibria between imidazole and inorganic phosphate is comparable in magnitude with the acoustic absorption observed in some intact tissues.

• The International Journal of Costume Culture
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• v.5 no.2
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• pp.53-65
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• 2002

Morphology of polyester fiber was physically modified by solvent treatment. PET fiber was treated with N,N-dimethylformamide (DMF) at 100, 120, $140^{circ}C$ for 10 minutes without tension. The structural changes in the morphology of DMF-induced modified PET fiber were FTIR and SEM analysis. Also dyeing behavior of DMF-treated polyester fibers with various disperse dyes was studied to detect changes of amorphous area in fine structure. DMF treatment resulted in increases in total void content, degree of crystallinity, trans isomer content, chain folding, segmental mobility and molecular packing, but it resulted in decreases in amorphous orientation, intermolecular forces and individual void size through longitudinal shrinkage, lateral welling and removal of oligomers. Void-size distribution could be estimated from the dye uptake with various sizes of disperse dyes. In contrast to the large increases in dye uptake with small dye molecules, there is no and little dye uptake with the bulkiest dye, which means that void size is bigger or smaller than the volume of each dye. Diffusion rates of dye molecules showed increases. This dyeing study revealed that the disperse dyeing is very effective method for characterizing the internal morphology of polyester fiber.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.142-148
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• 1972

The intermolecular orbital theory was applied to the Diels-Alder reaction of naphthalene, phenanthrene and 1,2-benzanthracene with maleic anhydride. The expected positions of thermal addition in the alternant bydrocarbons were in agreement with experiment. It was also possible to explain the relative proportions of two isomeric adducts with the calculated stabilization energies. Comparison of the results with paralocalization energies of Brown gave agood linear correlation.