Satoko Nishiyama

Optical and electrical characterization of plasma polymerized pyrrole films

Plasma polymerization of pyrrole was carried out in the presence and absence of iodine, and the resulting films were characterized by optical and electrical means. Their infrared spectra were very similar to each other, suggesting that iodine was neither bonded in any manner to, nor strongly interacting with, the pyrrole polymer chains. Based on their infrared spectra, a chemical structure was proposed for the plasma-polymerized pyrrole (PPPy) film. An analysis of the electronic spectra gave band gap energies of 1.3 and 0.8 eV for the undoped and doped PPPy films, respectively. In line with this result, the current–voltage characteristics of the two types of polymer films revealed that the conductivity of the doped PPPy film was approximately two times greater than that of the undoped one. An investigation of the scanning electron micrographs led us to conclude that iodine had changed the surface morphology of the PPPy film, resulting in the small increase in conductivity. A detailed analysis of the condu...

Luminescence of Betaine-30 Dispersed in Polymeric Solids

Emission spectra and excitation emission matrix of Betaine-30 (B30) dispersed in polymeric solids were determined. Emission wavelength was different for each polymer. The maximum wavelength became long with increasing the polarity of the polymer. A new possibility to determine the polarity of the medium using B30 was suggested.

Optical Properties of Poly(Propylene Carbonate) which Contains C60(OH)n Structure in the End of Polymer Chain

ABSTRACT Poly(propylene carbonate) which contains C60(OH)n structure in the end of polymer chain was synthesized by copolymerization of propylene oxide and CO2 with Et2Zn-C60(OH)n catalytic system. Emission and absorption spectra of the product polymer were determined and discussed. An emission band with a few peaks in UV-region were seen in the emission spectrum.

Effects of Molecular Structure on Luminescent Properties of Betaine Dyes

We compared spectral properties of Betaine-30 (B30) with other similar betaines or triphenylpyridine. They showed similar UV-absorption and shorter emission spectra in polymeric solids. The emission wavelength appeared to be red shifted with increasing polarity of the solvent or CT characteristics of dye molecule. Other dyes would be able to be used as B30 for a kind of polarity indicators, furthermore, B30 appeared to be most stable among them. We also compared their semiempirical M.O. calculation results. INDO/S calculations showed CT characteristics of their absorption bands in visible region.

Environmental Effects on Photochemical Properties of Betaine Dyes in Rigid Media

We report luminescence of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate (B30)- or other betaine dye-dispersed rigid media at 77 K and at room temperature (r.t.). Their luminescence in acetone at 77 K were remarkably influenced by water addition. UV-excited blue ∼ bluish green luminescence of B30-dispersed polymers at r.t. we reported in our previous reports appeared to resemble that of B30-dispersed acetone at 77 K in the presence of water. It suggests the participation of protonation and/or deprotonation processes in the UV-excited states of B30. A weak emission shoulder in visible emission wavelength range was also observed for B30-dispersed polymeric solids at r.t., similar to those emission bands for betaine dye-dispersed polymeric solids or organic solvents at 77 K.

Ultraviolet Irradiation Effects on and Depth Profiles in X-ray Photoelectron Spectra of Poly(vinylpyridine) Thin Films

The N 1s core binding energies of spin-coated poly(vinylpyridine) (PVPy), quaternized PVPy, and UV-irradiated PVPy were determined using X-ray photoelectron spectroscopy, and the depth profiles were determined using Ar+ beam etching. In typical N 1s spectra, cationic nitrogen atoms appeared at a binding energy 2–3 eV higher than that of neutral pyridine (Py). Changes in alkylpyridiniums in N 1s and bromide in Br 3p were determined according to etching cycles. In our PVPy cases, two types of nitrogen appeared at a region of high energy compared with that of neutral Py, and the differences in the binding energies between those states and neutral Py were all less than 2 eV. These nitrogens can be assigned to hydrogen-bonded Py and a complex formed among Py rings. Neutral Py, the complex Py, and hydrogen-bonded Py are very close together, and they were located at 399.0, 399.7, and 400.6 eV, respectively. Traces of ionic species were observed only in IR spectra.

Synthesis and Characterization of a Fullerene Derivatives

Through this paper we are proposing chemically modified fullerol as a fluorescent indicator. We examined the esterification of a fullerol, C60(OH)n, and determined the emission properties which have been directly linked to their chemical structures. As “fullerol” is a mixture of polyhydroxylated fullerenes, the separation of C60(OH)n and their esters have been attempted by using polyacrylamide gel electrophoresis (PAGE).