• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1333-1335
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• 1997

We have made disperse diazo black D(DBD) thin films using Langmuir-Blodgett(LB) and vacuum-evaporation technique. Physical and optical properties of the films were investigated. Solution was made with a concentration of $10^{-3}mol/{\ell}$ using chloroform. Moving wall apparatus, (NL-LB140S-MWC) was employed to make the LB films. X,Y and Z-type LB films were manufactured and studied UV/visible absorbance spectra and morphology of surface using atomic force microscopy(AFM). Vacuum-evaporated DB D thin films were made at a pressure of $10^{-5}$ torr. The absorption peaks were observed at 200 and 400 nm in the LB films and vacuum-deposited films. We have also studied photoluminescence spectrum of the DBD films.

• Journal of the Korean Applied Science and Technology
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• 제30권4호
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• pp.754-760
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• 2013

We investigated an electrochemical properties for Langmuir-Blodgett (LB) monolayer films of sphingomyelin(SP) and polyamic acid(PAA) mixture(1:1, 2:1 and 3:1 molar ratio). LB monolayer films of mixture was deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system in 0.1N $KClO_4$ solution. As a result, LB monolayer films of SP and PAA mixture was appeared on irreversible process caused by the reduction current from the cyclic voltammogram. Diffusion coefficient(D) in the SP and PAA mixture was calculated $2.670{\times}10^{-5}$, $3.562{\times}10^{-5}$ and $1.005{\times}10^{-5}cm^2s^{-1}$ at 1:1, 2:1 and 3:1 molar ratio, respectively.

• Journal of the Korean Applied Science and Technology
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• 제30권1호
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• pp.64-70
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• 2013

We investigated an electrochemical properties for Langmuir-Blodgett (LB) monolayer films of sphingomyelin and polyamic acid(1:1 molar ratio) mixture. LB monolayer films of mixture was deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system in $KClO_4$ solution. The current of reduction and oxidation range was measured from 1650 mV to -1350 mV, continuously. The scan rates were 50, 100, 150, 200 and 250 mV/s, respectively. As a result, LB monolayer films of sphingomyelin and polyamic acid mixture was appeared on irreversible process caused by the reduction current from the cyclic voltammogram. Diffusion coefficient (D) in the sphingomyelin and polyamic acid mixture was calculated $2.67cm^2s^{-1}{\times}10^5$, $5.23cm^2s^{-1}{\times}10^6$ at 0.1 N and 0.2 N $KClO_4$ solutions, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.166-169
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• 1996

It is well known that the metallo-phthalocyanines (MPcs) are sensitive to toxic gaseous molecules such as NO$_2$ and also chemically and thermally stable and it is recently reported that SnO$_2$ thin films have a selective sensitivity to NO$_2$ and SO$_2$ gas. Therefore, it is interesting to prepare phthalo-cyanine Langmuir-Boldgett(LB) films containing tin as a chemical sensor for NO$_2$ and SO$_2$ gas and test the selectivity with these tin containing LB films. First, in this study, ultra thin films of Octa (2-ethylhexyloxy) tin-phthalocyanine were prepared on various substrates by LB method. $\pi$-A isotherm and transfer characteristics of these films were investigated. The formation of these films was determined by ellipsometry. Intrinsic current-voltage(I-V) characteristics of these films were also measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.273-276
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• 1997

This paper describes the thermally stimulated current (TSC) measurements of arachidic acid and polyamic acid alkylamine salt(PAAS) LB film, which is a precursor of polyimide(PI). The measurements were performed from room temperature to about 25$0^{\circ}C$ and the temperature was increased at a rate of 0.02 K/s linearly. It shows that peaks of TSC are observed at about 8$0^{\circ}C$ in the arachidic acid and about 8$0^{\circ}C$, 16$0^{\circ}C$ in the PAAS LB films. Results of these measurements indicate that one peak at 8$0^{\circ}C$ is resulted from alkyl group; the other peak at 16$0^{\circ}C$ is due to alkyl and C-O group of PAAS. Additional large peak at about 16$0^{\circ}C$ is due to dipole moments in the PAAS films. The DSC of PAAS, arachidic acid and octadesylamine are measured. Thermal imidization was performed at 30$0^{\circ}C$ for 1 hour by our pre study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.199-202
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• 1996

This paper describes the thermally stimulated current (TSC) measurements of arachidic acid and polyamic acid alkylamine salt(PAAS) LB film, which is a precursor of polyimide(PI). The measurements were performed from room temperature to about 25$0^{\circ}C$ and the temperature was increased at a rate of 0.02 K/s linearly. It shows that peaks of TSC are observed at about 8$0^{\circ}C$ in the arachidic acid and about 8$0^{\circ}C$, 16$0^{\circ}C$ in the PAAS LB films. Results of these measurements indicate that one peak at 8$0^{\circ}C$ is resulted from alkyl group; the other peak at 16$0^{\circ}C$ is due to alkyl and C-O group of PAAS. Additional large peak at about 16$0^{\circ}C$ is due to dipole moments in the PAAS films. The DSC and TGA of PAAS, arachidic acid and octadesylamine are measured. Thermal imidization was performed at 30$0^{\circ}C$ far 1 hour by our pre study

• Bulletin of the Korean Chemical Society
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• 제23권4호
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• pp.575-579
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• 2002

Two-dimensionally cross-linked ultrathin films of poly(maleic acid-alt-methyl vinyl ether) (MA-MVE) and poly(allylamine) (PAA) were produced by using sodium dioctadecyl sulfate (2C18S) as the monolayer template for Langmuir-Blodgett (LB) depositio n. The template molecules were subsequently removed by thermal treatment followed by extraction. The polyion-complexed monolayers of three components, i.e., template 2C18S, co-spread PAA, and subphase MA-MVE, were formed at the air-water interface. Their monolayer properties were studied by the surface pressure-area isotherm. The monolayers were transferred on solid substrates as Y type. The polyion-complexed LB films and the resulting network films were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The cross-linking to form a polymer network was achieved by amide or imide formation through heat treatment under a vacuum. SEM observation of the film on a porous fluorocarbon membrane filter (pore diameter 0.1 ㎛) showed covering of the pores by four layers in the polyion complex state. Extraction by chloroform followed by heat treatment produced hole defects in the film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제14권9호
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• pp.757-761
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• 2001

We studied emitting properties of organic electroluminescent devices fabricated using the spin-coating and Langmuir-Blodgett(LB) technique. The LB technique has the advantage of precise control of the thickness better than spin-coating method. LB monolayer of poly(3-hexylthiophene)(P3HT) was deposited 27 layers onto the indium-tin-oxide(ITO) substrate as Y-type films by the vertical dipping method. In the absorption spectra, the λ$\_$max/ of P3HT-AA LB films and of spin-coating films showed about at 510, 545 and 590 nm corresponding to 2.43, 2.28, 2.10eV. And we observed that the turn-on voltage of devices deposited by LB method(10V) was higher than that of spin-coating method(8.5V) in voltage-current-luminance characteristic. In the logV-logJ characteristics of ITO/P3HT-AA LB/Al device, we confirmed that El device fabricated by LB method follows three conduction mechanisms: ohmic, space-charge-limited current(SCLC) conduction and trapped-carrier-limited space-charge current(TCLC) conduction.

• Macromolecular Research
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• 제11권1호
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• pp.2-8
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• 2003

The self-assembly of polymers can lead to supramolecular systems and is related to the their functions of material and life sciences. In this article, self-assembly of Langmuir-Blodgett (LB) films, polymer micelles, and polymeric nanoparticles, and their biomedical applications are described. LB surfaces with a well-ordered and layered structure adhered more cells including platelet, hepatocyte, and fibroblast than the cast surfaces with microphase-separated domains. Extensive morphologic changes were observed in LB surface-adhered cells compared to the cast films. Amphiphilic block copolymers, consisting of poly(${\gamma}$-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) [or poly(N-isopropylacrylamide) (PNIPAAm)] as the hydrophilic one, can self-assemble in water to form nanoparticles presumed to be composed of the hydrophilic shell and hydrophobic core. The release characteristics of hydrophobic drugs from these polymeric nanoparticles were dependent on the drug loading contents and chain length of the hydrophobic part of the copolymers. Achiral hydrophobic merocyanine dyes (MDs) were self-assembled in copolymeric nanoparticles, which provided a chiral microenvironment as red-shifted aggregates, and the circular dichroism (CD) of MD was induced in the self-assembled copolymeric nanoparticles.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2547-2552
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• 2010

CdS nano-particulate films were prepared at the air/water interface under Langmuir monolayers of arachidic acid (AA) via interfacial reaction between $Cd^{2+}$ ions in the subphase and $H_2S$ molecules in the gaseous phase. The films were made up of fine CdS nanoparticles with hexagonal Wurtzite crystal structure after reaction. It was revealed that the formation of CdS nano-particulate films depends largely on the experimental conditions. When the films were ripened at room temperature or an increased temperature ($60^{\circ}C$) for one day, numerous holes were appeared due to the dissolution of smaller nanoparticles and the growth of bigger nanoparticles with an improved crystallinity. When the films were ripened further, CdS rodlike nanoparticles with cubic zinc blende crystal structure appeared due to the re-nucleation and growth of CdS nanoparticles at the stacking faults and defect structures of the hexagonal CdS grains. These structures were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and X-ray diffraction (XRD). These results declare that CdS semiconductor nanoparticles formed at the air/water interface change their morphologies and crystal structures during the ripening process due to dissolution and recrystallization of the particles.