Sang-Burm Jung

Fabrication and electrical properties of dendritic macromolecule thin films based on metal complexes

Abstract We attempted to fabricate the dendrimer LB films containing a 48 pyridylpropoxy end functional group. The pyridylpropoxy functional group could form a complex structure with metal ions. The samples for electrical properties were fabricated in two ways using metal ions complex by the LB method. In addition, we have investigated the surface activity at the air–water interface as well as the electrical properties for the monolayers LB films of pure G4-48PyP dendrimer and its complex with metal ions (Pt 4+ and Fe 2+ ions). In the π– A isotherms of the dendrimers, the stable condensed films formed at the air–water interface and the effect of metal ions showed a difference in molecular behavior. And we have investigated the electrical properties of the ultra-thin dendrimer LB films by the I – V characteristics of metal/insulator/metal structure. There is a difference between pure G4-48PyP dendrimer LB film and its complex metal ions. This has been generated by the metal ions’ effect. We think that these differences occur by the build up of multi-layers by complex process in the flask and concentration of metal ions in subphase. Therefore, the metal ion around G4-48PyP dendrimer can contribute to the formation of network structure among dendrimers and this result affects the change in electrical properties.

Effect of Complex On Electrical Properties of Dendrimer Langmuir-Blodgett Films Containing 48 Pyridinealdoxime

Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. And one of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer Langmuir–Blodgett (LB) films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current–voltage characteristics of metal/dendrimer LB films/metal (MIM) structure. The rectifying behavior of the devices was occurred in applied field. And result in change of electrical properties by the effect of complex with metal ions.

Electrical properties of dendritic macromolecule containing azo-groups

We synthesized the G4-48Azo dendrimer functionlized with azobenzene groups, fully reversible photo-isomerization reaction, in their periphery. We investigated monolayer behavior and its characteristics at air-water interface by LB method. And we observed the difference of molecular behavior and measured the surface pressure shift by 365[nm]light irradiation because of the photo-isomerization of the azobenzene group in their periphery. The electrical properties of the G4-48Azo dendrimer were compared with between trans form and cis form using metal/dendrimer LB film/metal(MIM)structure and STM system. And we obtained the difference of values in I-V characteristics using STM originating from the photo-isomerization of the azobenzene.

Fabrication and Electrical Properties of Dendrimer Langmuir-Blodgett Films Based on Metal Complex

We attempted to fabricate dendrimer Langmuir-Blodgett (LB) films containing a 48 pyridylpropoxy functional end group. The pyridylpropoxy functional group could form a complex structure with metal ions; in this study, the samples for the electrical measurement were fabricated using two types of metal complexes with Pt4+ and Fe2+ ions by the LB method. In addition, we investigated the surface activity at the air-water interface as well as the electrical properties of the mono layers of a pure G4-48PyP dendrimer and its complex with metal ions (Pt4+ and Fe2+ ions). In the surface pressure-area (?-A) isotherms of the dendrimers, the s table condensed films formed at the air-water interface and the metal ions effect showed a difference in molecular behavior. We also investigated the electrical properties of ultrathin dendrimer LB films by studying the current-voltage (I?V) characteristics of the metal/insulator/metal (MIM) structure. In conclusion, it is shown that the metal ion around the G4-48PyP dendrimer can contribute to the formation of the network structure of dendrimers, which results from the change in electrical properties.

Electrical Properties of G4-48PyP Dendrimer LB Films

We attempted to fabricate a G4-48PyP dendrimer LB films containing 48 pyridinepropanol functional end group that could form a complex structure with metal ions. Also, we investigated the surface morphology activity of dendrimer films. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the dendrimer LB films were investigated by studying the current-voltage characteristics of metal/dendrimer LB films/metal (MIM) structure. Rectifying behavior of the devices was occurred in applied field.

Fabrication of Crosslinked Phenolic Polymer LB Films and Its Electrical Properties

Abstract We fabricated the crosslinked films using p-hexadecoxyphenol (p-Hp), which is amphiphilic phenol and can form polyion complexes with formaldehyde at the air-water interface. The behavior of monolayers at the air-water interface and the surface structure of LB films was investigated by Brewster angle microscope (BAM) and scanning Maxwell-stress microscope (SMM), respectively. We have provided evidence for the high insulating performance of phenol-formaldehyde thin films by the LB method.

Electrical Properties for Insulation Layers of Phenolic Polymer Thin Films

Abstract We have fabricated the crosslinked Langmuir-Blodgett (LB) films using amphiphilic phenol, p-hexadecoxyphenol (p-HP), which can form polyion complexation with formaldehyde at the air-water interface. The conductivities of p-HP LB films are as follows: heat-treatment of 1% formaldehyde subphase (3.76×10−15∼4.76×10−15 S/cm)<1% formaldehyde subphase (7.36×10−15∼8.34×10−15S/cm)<pure water (1.33×10−14∼1.74×10−14S/cm). Also, relative dielectric constants of p-HP LB films were reduced from 5.76∼8.23 (pure water) to 2.47∼2.73 (heat-treatment of 1% formaldehyde subphase).

Electric Properties of the IMI-O Polymer Complexed in Metal Ion

Abstract Poly(N-(2–4-imidazolyl) ethyl) maleimide-alt-1-octadecene (IMI-O) polymer which can complex metal ion, was used to confirm the possibility of molecular device made by Langmuir-Blodgett method. Metal/Insulator/Metal (MIM) device was fabricated for investigating electric properties of LB film which was complex with metal ion. In the π-A. isotherm, the surface pressures at collapse point are different as to the molecular weight of metal ions respectively. The current of LB films which were complex with metal ion had a difference as to the kinds of metal ion.

Electric and dielectric properties in MIM structure of copolymer LB films

We investigated electric and dielectric properties of metal/insulator/metal (MIM) device using maleate copolymer LB films. The thickness of maleate copolymer LB film measured by ellipsometry and X-ray diffraction was about 27-30[/spl Aring/]. The maleate copolymer LB films have the property of insulators such as organic ultra-thin films. The electrical conduction mechanism was Schottky current determined by the measurement of current-voltage characteristics, and its conductivity was 10/sup -14/-10/sup -15/ [S/cm]. Dielectric constant was about 5.0-6.0 using various measurement methods: I-V and frequency-dependent dielectric properties. Schottky barrier was about 0.9-1.0[eV]. The activation energy was 0.74 [eV] from the measurement of current-temperature characteristics. The frequency-dependent dielectric properties involved orientational polarization by the dipole.