• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.458-460
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• 2000

We attempted to fabricate polyurethane derivatives (PU-CN, PU-DCM) LB films by using LB method. Also, we investigated the monolayer behavior at the air-water interface by surface pressure-area ($\pi$-A) isotherms. And, the surface morphologies and the physicochemical properties of LB films were investigated by atomic force microscopy (AFM) and UV-vis spectroscopy, respectively. Also, the electrical properties of polyurethane derivatives LB films were investigated by using the conductivity, the dielectric constant and activation energy. In the surface morphologies, physicochemical, electrical properties of polyurethane derivatives LB films, the properties is different as to the Polyurethane derivatives, it is considered that this phenomena could be described by the difference of lumophore pendant which was adhered at PU main chain.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.357-368
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• 2003

II-A isotherms and phase behaviors of 'tocomide', a newly synthesized 1,3-bis(N-(2-hydroxyethyl)-tocopherol succinylamino)-2-hydroxypropane, mixed with cholesterol and linoleic acid, was studied for its monolayer miscibility and a stable delivery formulation for antioxidant applications. The monolayer of tocomide and cholesterol was formed in a homogeneously mixed state at air-water interface. The ternary mixtures with linoleic acid showed various bulk structures, including a stable and transparent solution of thermodynamically stable lamellar phase. The lamellar structure was confirmed by the X-ray diffraction (XRD) patterns and polarized microscopy such that pure tocomide formed a liquid crystal at room temperature with a lamellar periodicity of 36.7 $\AA$(2$\theta$=2.41$^{\circ}$).

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.753-759
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• 1992

For the fabrication of the microscale memory or electrical devices, Langmuir-Blodgett(LB) method is the most possible candidate. N-Alkylquinolium-TCNQ compounds were synthesized. The structure of the compounds were identified by the NMR spectroscopy and the purity were checked to be good by the elemental analysis. The surface pressure($\pi$) was measured at the air-water interface. The isotherm showed two transitions at 30mN/m and 45mN/m. The LB films were deposited by the home-made Kuhn type apparatus. The transfer ratio($\tau$) of the deposition was more than 0.95 for the up-stroke and less than 0.4 for the down-stroke. The absorbance peaks of the LB films appear at around 420nm and 700-820nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.317-319
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• 2000

We fabricated the QCM with Langmuir-Blodgett(LB) film deposited at the different subphase pH and investigated the resonant frequency response by the injection of organic gas response. In the $\pi$-A isotherms, the monolayer on the air/water interface had different limiting area per molecule and showed more condensed status as increasing the subphase pH. When palmitic acid LB film was deposited on the QCM, the resonant frequency shift was proportional to the deposited layer and had more resonant frequency shift in the case of the higher pH range as expected. In the resonant frequency for the injection of organic gas, it has been improved in the case of LB film fabricated at the lower subphase pH range and dependant upon the molecular weight of organic gas.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.320-323
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• 2000

We attempted to fabricate polyurethane derivatives (PU-CN, PU-DCM) LB films by using LB method. Also, we investigated the monolayer behavior at the air-water interface by surface pressure-area ($\pi$-A) isotherms. And, the surface morphologies and the physicochemical properties of LB films were investigated by atomic force microscopy (AFM) and UV-vis spectroscopy, respectively. Also, the electrical properties of polyurethane derivatives LB films were investigated by using the conductivity and the dielectric constant. In the AFM images, we conclude that surface morphology of PU-DCM LB films is smooth and homogeneous and has optimal hydrophobicity and good stability, whereas PU-CN LB films give rougher surfaces with more excess material. In the I-V characteristics, the conductivity is different as to the polyurethane derivatives, it is considered that this phenomena could be described by the difference of lumophore pendant which was adhered at PU main chain.

• Electrical & Electronic Materials
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• v.10 no.6
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• pp.548-554
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• 1997

We fabricated the sample of ultra thin lipid membrane(L-$\alpha$-DLPC) by LB method. The $\pi$-A isotherm of the DLPC was measured at the air-water interface varying with the compressing speed and amounts of solutions for spreading. For the good property of lipid monolayer film, it was necessary to prepare at the lower speed of compressing, with an appropriate volume of solutions for spreading. Absorption, transmitance and intensity with the UV spectrophotometer were measured. The Z-type multilayers showed good characteristics better than Y-type. So we found building-up of structurally high quality LB films is essential to study properties of the films and to get reproducible data.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.595-598
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• 1999

Ultra-thin films of amphiphilic Squarylium dye were prepared on the hydrophilic glass substrate by Langumuir-Blodgett(LB) technique. From the measurement of the surface pressure-area($\pi$-A) isotherm at air-water interface, it was found that amphiphilic Squarylium dye can form the stable monolayers. Using the LB technique, the Z-type monolayer assembly can be obtained. The amphiphilic Squarylium dye LB films exhibit λ\ulcorner at 684nm. The absorption is significantly red-shifted from solution of amphiphilic Squarylium dye(637nm in chloroform), suggesting that the Squarylim chromophores form J-aggregate in the LB film.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.4
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• pp.377-383
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• 2005

This paper deals with the flow characteristics of air-water two-phase flow in a vertical tube of 10mm I.D. and 600mm in length at an adiabatic condition. The obtained experimental data were covered with the liquid superficial velocity ranging from 0.095m/s to 2.56m/s. and the gas superficial velocity ranging from 0.032m/s to 21.08m/s. The effects of the gas and liquid superficial velocity on the flow pattern transitions, frictional pressure drop, and film thickness and gas-liquid interface roughness were also examined. It was found that the film thickness increased and the liquid film wave length was more longer with the liquid superficial velocity $j_L$ increasing at $j_G$ constant. It was also showed that the frictional pressure drops were experienced in three regions. namely increasing region(bubbly flow), decreasing region (Taylor bubble and slug flows) and re-increasing region (annular flow).

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.493-498
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• 1995

Ultrathin networks of itaconic acid copolymers and poly(allylamine) were produced by a Langmuir-Blodgett (LB) technique employing a double-chain amine as a monolayer template which was subsequently removed by extraction after thermal crosslinking. Itaconic acid copolymers used were copoly (itaconic acid-ethyl vinyl ether) and copoly (itaconic acid-n-butyl vinyl ether). The polyion-complexed monolayers of three components consisting of template amine, itaconic acid copolymer and poly (allylamine) were formed at the air-water interface. The Langmuir film properties have been studied by the surface pressure-area isotherm and fluorescence microscopy. The monolayers were transferred on solid substrates and were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). Two-dimensional polymer networks were formed through imide or amide linkages by heat treatment under vacuum. The heat-treated films were extracted with chloroform after immersion in aq. sodium chloride to remove the template amines. SEM observation of a LB film on a porous fluorocarbon membrane filter with pore diameter of 0.1 μm showed covering of the pores by six layers in the polyion complex state.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.417-428
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• 2018

In this study, we fabricated hierarchically self-assembled thin films composed of graphene oxide (GO) sheets and gold nanoparticles (Au NPs) using the Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques and investigated their gas-sensing performance. First, a thermally oxidized silicon wafer ($Si/SiO_2$) was hydrophobized by depositing the LB films of cadmium arachidate. Thin films of ligand-capped Au NPs and GO sheets of the appropriate size were then sequentially transferred onto the hydrophobic silicon wafer using the LB and the LS techniques, respectively. Several different films were prepared by varying the ligand type, film composition, and surface pressure of the spread monolayer at the air/water interface. Their structures were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their gas-sensing performance for $NH_3$ and $CO_2$ was assessed. The thin films of dodecanethiol-capped Au NPs and medium-sized GO sheets had a better hierarchical structure with higher uniformity and exhibited better gas-sensing performance.