• Bulletin of the Korean Chemical Society
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• v.23 no.4
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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.

• Membrane Journal
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• v.5 no.2
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• pp.89-96
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• 1995

The monolayer characteristics of phosphate amphiphiles with azobenzene at air/water interface were studied by the measurment of $\pi-A$ curves and absorption spectra. Immediately after being spread on the water surface, these amphiphiles having strong intermolecular hydrogen bonding interactions showed the typical absorption spectra which resulted from domain formation. But the aggregated domains could be controlled by changing the subphase conditions (adding bulky salt and rasing pH). Addition of metal ions in subphase changes the molecular orientation of monolayer. As the metal ion charge increases ($1\leq2$ < 3 < 4 valence), the absorption maximum (310nm) of the amphiphile with azobenzene shifts to a longer wavelength (350nm) which means that the orientation of the amphiphile is tilted. These results suggest that the molecular orientation, and furthermore the aggregation state of monolayer can be possibly controlled by the interaction of metal ions with different charge types.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.121-123
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• 2001

We synthesized dendrimers containing light switchable units such as azobenzene group at the air/water interface. Their chemical structure was verified by using NMR study and UV spectroscopy. We firstly investigated the monolayer behavior and by light irradiation using $\pi$-A isotherm at the air/water interface. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photo-switching behavior by the isomerization of azobenzene group in their periphery. This suggests that optical behavior and morphological change are affected by the functional group and the symmetric chain.

• Journal of the Korean Applied Science and Technology
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• v.15 no.2
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• pp.33-39
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• 1998

Displacement current measuring technique has been applied on the study of monolayers of functional polyimide containing azobenzene derivatives. The displacement current was generated from monolayers on the water surface by monolayer compression and expansion. Displacement current was generated when the area per molecule was about $70{\AA}^2$ and $100{\AA}^2$. Displacement currents were investigated in connection with monolayer of long chain alkylamines. It was found that the maximum of displacement current appeared at the molecular area just before the initial rise of surface pressure in compression cycles of polyamic acid and long chain alkylamines.

• Journal of the Korean Applied Science and Technology
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• v.14 no.3
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• pp.55-61
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• 1997

Maxwell displacement current(MDC) measuring technique has been applied on the study of monolayers of polyamic acid containing p-cyanoazobenzene. The displacement current was generated from monolayers on the water surface by monolayer compression and expansion. Displacement current was generated when the area per molecule was about $140{\AA}^2$ and $100{\AA}^2$. Maxwell displacement currents were investigated in connection with monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles.

• Journal of Integrative Natural Science
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• v.6 no.4
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• pp.215-219
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• 2013

In this study, in order to investigate how consecutive treatments of glass surface with HF acid and water vapor/Ar plasma affect the quality of 3-aminopropyltriethoxysilane self-assembled monolayer (APS-SAM), poly(3,4-ethylenedioxythiophene) (PEDOT) thin films were vapor phase-polymerized immediately after spin coating of FeCl3 and poly-urethane diol-mixed oxidant solution on the monolayer surfaces prepared at various treatment conditions. For the film characterization, various poweful tools were used, e.g., FE-SEM, an optical microscope, four point probe, and a contact angle analyzer. The characterization revealed that a well prepared APS-SAM on a glass surface treated with water vapor/Ar plasma is very useful for uniform coating of FeCl3 and DUDO mixed oxidant solution, regardless of HF treatment. On the other hand, a bare glass surface without APS-SAM but treated with HF and water vapor/Ar plasma generally led to a very poor oxidant film. As a result, PEDOT films vapor phase-polymerized on APS-SAM surfaces are far superior to those on bare glass surfaces in the quality and electrical characteristics aspects.

• Macromolecular Research
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• v.12 no.1
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• pp.127-133
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• 2004

We have studied the surface micelle formation of polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) at the air-water interface. A series of four PS-b-P2VPs were synthesized by anionic polymerization, keeping the PS block length constant (28 kg/㏖) and varying the P2VP block length (1, 11, 28, or 59 kg/㏖). The surface pressure-area ($\pi$-A) isotherms were measured and the surface morphology was studied by atomic force microscopy (AFM) after Langmuir-Blodgett film deposition onto silicon wafers. At low surface pressure, the hydrophobic PS blocks aggregate to form pancake-like micelle cores and the hydrophilic P2VP block chains spread on the water surface to form a corona-like monolayer. The surface area occupied by a block copolymer is proportional to the molecular weight of the P2VP block and identical to the surface area occupied by a homo-P2VP. It indicates that the entire surface is covered by the P2VP monolayer and the PS micelle cores lie on the P2VP monolayer. As the surface pressure is increased, the $\pi$-A isotherm shows a transition region where the surface pressure does not change much with the film compression. In this transition region, which displays high compressibility, the P2VP blocks restructure from the monolayer and spread at the air-water interface. After the transition, the Langmuir film becomes much less compressible. In this high-surface-pressure regime, the PS cores cover practically the entire surface area, as observed by AFM and the limiting area of the film. All the diblock copolymers formed circular micelles, except for the block copolymer having a very short P2VP block (1 kg/㏖), which formed large, non-uniform PS aggregates. By mixing with the block copolymer having a longer P2VP block (11 kg/㏖), we observed rod-shaped micelles, which indicates that the morphology of the surfaces micelles can be controlled by adjusting the average composition of block copolymers.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.26-30
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• 2004

Orientation control of a polyoxometalate (POM) nanoparticle in its two-dimensional arrangement was attempted by Langmuir-Blodgett (LB) technique. For their uniorientation, two carboxyl groups were introduced on one side of the POM particle, and hydrophobic long chains were attached by esterification with the carboxyl groups (C18-POM). The C18-POM layer spread on water surface showed stability against surface pressure up to 60 mN/m. The pattern of the C18-POM isotherm was quite different from stearyl alcohol (C18-OH), while the POM itself did not show any development of surface pressure on water surface. The AFM images of C18-POM LB films showed some microcrystalline structures that were noticed as dot structures by Brewster angle microscopy. The microimages for C18-POM did not completely spread out as a monolayer on the water surface. The XPS spectra indicated the presence of POM structures and stearyl ester bonds formed from about 65% of the total carboxyls. The XRD spectra showed that the unioriented POMs were not positioned with the same lattice distance but rather in a wavy surface state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.904-907
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• 2003

We synthesized dendrimers containing light switchable units, azobenzene group. To apply to the molecular level devices or data storage system using Langmuir-Blodgett(LB) film, we firstly investigated the monolayer behavior using the surface pressure-area(${\pi}-A$) isotherms at air-water interface. And then the surface pressure shift of monolayer by light irradiation was also measured to the dendrimer with azobezene group. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photo-switching behavior by the isomerization of azobenzene group in their periphery. This results suggest that the dendrimers with azobenzene group can be applied to high efficient nano-device of molecular level. And we measured the electrical properties by MIM and STM. The dendrimer with azobenzene group compared trans form and cis form at electrical properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.695-701
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• 2002

Maxwell displacement current (MDC) measuring technique has been applied on the study of monolayers of fatty acid and polyamic acid mixture. The displacement current was generated from monolayers on the water surface by monolayer compression and expansion. Displacement current was generated when the area per molecule was about 132 $^2$and 115 $^2$just before the initial rise of the surface pressure during the 1st and 2nd mixed monolayer compressions cycle, respectively. Maxwell displacement currents were investigated in connection with mixed monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles. Ultra thin film of fatty acid and polyamic acid mixture was prepared on the hydrophilic quartz plate by Langmuir-Blodgett (LB) method. The precursor LB film was heated in a vacuum dry oven at 12$0^{\circ}C$ in order to convert it into the LB film of polyimide. The absorption spectra of LB films were also induced photoisomerization by UV and visible light irradiation.