• Bulletin of the Korean Chemical Society
• /
• v.15 no.5
• /
• pp.369-374
• /
• 1994

Self-assembled (SA) and Langmuir-Blodgett (LB) monolayers of arachidic acid on silver surfaces have been investigated by a reflection-absorption Fourier transform infrared spectroscopy. Arachidic acid was adsorbed on silver as carboxylate with its two oxygen atoms bound symmetrically to the surface. Although both the SA and LB monolayers consisted of fully extended trans zigzag carbon chains, a closer examination indicated that the SA monotayers should possess a more ordered crystalline structure than the LB monolayers. The infrared spectral data dictated that the extent of methyl group exposure at the air-film interface was greater in the SA monolayers than the LB monolayers, in agreement with the contact angle measurement. From a theoretical analysis, the alkyl chains in each monolayers seemed to be tilted away from the surface normal by less than $3.5^{\circ}$, but in opposite directions. Arachidic acid monolayers were concluded to have same structure as stearic acid monolayers.

• Macromolecular Research
• /
• v.11 no.6
• /
• pp.476-480
• /
• 2003

The rate of hydrolysis of Langmuir monolayer films of biodegradable polylactide (PLA) derivates was investigated at the air/water interface. The present study investigated such parameters as surface pressure, pH, and time. The hydrolysis of polyester monolayers depended strongly on the subphase pH, the concentration of active ions. Under the conditions studied here, polymer monolayers showed faster rates of hydrolysis when they were exposed to a basic subphase rather than they did when exposed to acidic or neutral subphases. By increasing the concentration of the degradation medium, the hydrolytic rate of dl-PLA monolayers was accelerated (accelerating effect). In addition, the basic hydrolysis of modified PLA with small amounts of hydrophilic (benzyloxycarbonyl) methyl morpholine-2,5-dione or glycolide was much faster than that of the PLA homopolymer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.279-282
• /
• 2000

The displacement current measurement has been employed to study the dielectric properties of Langmuir films. A method for determining the dielectric relaxation time $\tau$ of floating monolayers on water surface is presented. The displacement current flowing across monolayers is analyzed using a rod-like molecular model. It's revealed that the dielectric relaxation time $\tau$ of monolayers in the isotropic polar orientational phase is determined using a liner relationship between the monolayers compression speed $\alpha$ and the molecular maximum area $A_{m}$. The compression speed $\alpha$ was about 30, 40, 50mm/minmm/min

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.699-705
• /
• 1995

Monolayers of hypericin, a photodynamic polycyclic quinoidal compound, were prepared at the air-water interface, and were transferred to metal substrates to form Langmuir-Blodgett (LB) monolayers. The structural characteristics of hypericin LB monolayers and self-assembled (SA) monolayers were investigated using surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Both the spectroscopic data and the surface pressure - area (${\pi}-A$) isotherms suggest that hypericin forms ${\pi}-{\pi}$ aggregates that orient vertically to the subphase surface. Whereas the ordering and orientation of control was less effective in SA monolayers, a higher structural regularity was attained in LB systems. The effect of subphase on the structural integrity of the monolayer was also investigated.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.572-575
• /
• 2000

The highly efficient photoelectric conversion of chlorophyll a (Chl a) monolayers and multilayers was investigated. Using the Langmuir-Blodgett (LB) technique, Chl a monolayers and multilayers were fabricated onto optically transparent electrode, such as ITO glass. The photocurrent could be observed according to the light illumination. The action spectrum of the Chl a LB films was well consistent with its absorption spectrum. The possible application of the proposed system as a constituent of the artificial color recognition device was suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.113-117
• /
• 1995

The mechanism of the displacement current generation for stimulation transmit observed in the present displacement current measurement and theoretically analysed. The orientational change of molecules in monolayers was discussed on the basis of the Maxwell-displacement-current obtained. Maxwell displacement current was generated from monolayers on a water surface by monolayerr compression, and it measuring technique has been applied to the study of monolayers of Dipalmitoylphosphatidyl choline (L-${\alpha}$-DPPC). Finally, We measured that differential thermal analysis(DTA) of sample. Displacement current was generated when the area per molecule about 180${\AA}$$^2$in low pressure, and it was generated when the area per molecule about 110${\AA}$$^2$in high pressure. A result of DTA was showed that temperature at 124.6$^{\circ}C$.

• Tribology and Lubricants
• /
• v.19 no.6
• /
• pp.329-334
• /
• 2003

The antiwear properties of amphiphilic monolayers and composite multilayer on silicon surface were investigated using micro­tribometer and Auger Electron Spectroscopy. Langmuir­Blodgett (LB) monolayers from behenic acid, 2,4­heneicosanedione(HD) and its lopper complex((HD)$_2$Cu) were fabricated on silicon surface and the composite multilayer of 5­bilayer of (HD)$_2$Cu was fabricated on the surface of octadecyltrichlorosilane (OTS) self­assembled monolayer (SAM). We observed that LB monolayers and the composite multilayer exhibited a steady and excellent friction response when compared with the OTS SAM. These LB mono and multilayer also showed much higher wear­resistance than the OTS SAM.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.211-214
• /
• 2003

The tribological properties of amphiphilic monolayers and composite multilayer on silicon surface were investigated using micro-tribometer and Auger Electron Spectroscopy. Langmuir-Blodgett (LB) monolayers from behenic acid. 2.4-heneicosanedione(HD) and its copper complex((HD)$_2$Cu) were fabricated on silicon surface and the composite multilayer of 5-bilayer of (HD)$_2$Cu was fabricated on the surface of octadecyltrichlorsilane (OTS) self-assembled monolayer(SAM). We observed that LB monolayers and the composite multilayer exhibited a steady and excellent friction response when compared with the OTS SAM. These LB mono and multilayer also showed much higher wear-resistance than the OTS SAM.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.12
• /
• pp.1167-1172
• /
• 1995

A coverage of about 1 μm-sized pores of a membrane filter by four monolayers of maleic acids copolymers and poly(allylamine) (PAA) was attained by Langmuir-Blodgett (LB) technique through a covalent cross-linking followed a polyion complexation at the air-water interface. The copolymers were prepared to have side chains of hydrocarbon tail, carboxyl, and/or oligoether in the repeat unit. The surface pressure-area isotherms showed that the monolayers on an aqueous PAA have more expanded area than on pure water. The monolayers were transferable on a calcium fluoride substrate and a fluorocarbon membrane filter as Y deposition type, and the resulting LB films were characterized by FT-IR spectroscopy and scanning electron microscopy. A polymer network produced through interchain amide formation was confirmed in as-deposited films. The films were heat-treated in order to complete the cross-linking. SEM observation of the heat-treated film on a porous membrane filter showed that the four layer film was sufficiently stable to cover the filter pore of about 1 μm. Immersion of the film in water or in chloroform did not cause any change in its appearance on SEM and in FT-IR spectra.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.4
• /
• pp.316-320
• /
• 1995

The incorporation of metal ion into the Langmuir-Blodgett (LB) film of an itaconate copolymer was investigated. The polymer was prepared via radical copolymerization of monooctadecyl itaconate with triethyleneglycol methyl vinyl ether. The metal ions employed were Na+, Cs+, Mg2+, Fe2+, Al3+, and Fe3+. The surface pressure-area isotherms indicated that all the monolayers studied on subphases with metal ions showed more expanded areas than that observed on pure water. The monolayers showed an irreversible collapse behavior. The collapse pressure of the monolayers was low on subphases containing trivalent metal ions. From the FT-IR spectra by reflection and transmission modes, the formation of carboxylate salts and the uprisen orientation of the pendant against substrate surface in the polymer LB film were determined. It was estimated by XPS measurement that ca. 13.1 repeat units of the polymer contain one Na+ ion, while one Mg2+ ion corresponds to 5.9 carboxyls.