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Zhu, Z.; Maekawa, Yasunari; Koshikawa, Hiroshi; Suzuki, Yasuyuki; Yonezawa, Noriyuki*; Yoshida, Masaru
Nuclear Instruments and Methods in Physics Research B, 217(3), p.449 - 456, 2004/05
Times Cited Count：20 Percentile：76.47(Instruments & Instrumentation)The pretreatment effects using UV light illumination and DMF soaking on bulk and track etching rates of PET films were investigated. The wavelength of illuminated UV light plays an important role in sensitizing track etching. Illumination with the light at wavelengths longer than 320nm showed strong enhancement in the track etching rates without influence on the bulk etching rates, whereas light with the wavelengths lower than 320nm causes large enhancement in both track and bulk etching rates even in the interior of the material. The track etching rate is found to be not constant along ion tracks, which is attributed to the inhomogeneous distribution of reactive chemical species induced during post-UV light illumination. Furthermore, the DMF soaking of PET after UV light illumination can enhance the etching sensitivity of the track by more than 100 times. The phenomenon is attributed to the high diffusion of organic solution along tracks after UV light illumination.
Maekawa, Yasunari; Koshikawa, Hiroshi; Yoshida, Masaru
Polymer, 45(7), p.2291 - 2295, 2004/03
Times Cited Count：8 Percentile：28.47(Polymer Science)Ion track membranes of poly(ethylene terephthalate) (PET) are applied to the production of anisotropically conducting films possessing copper wires of less than sub-micron in diameter. The membranes possessing cylindrical pores of 1.9 
m and 200 nm in diameter were prepared by irradiation of 
Xe
ion beams followed by etching in an aqueous NaOH. Copper wires were deposited into the pores by electrochemical plating in aqueous copper sulfate solution to prepare the PET/Cu hybrid membranes. The copper wires with 1.9 m in diameter showed wavelike surface roughness, resulting from the roughness of the pore side wall, whereas the copper wires with 200 nm in diameter showed smooth surfaces. The resistances of the membranes measured by a four terminal resistance method are in good agreement with the calculated values, indicating that the hybrid membranes possess conductivity perpendicular to the membrane surfaces but not parallel to the surfaces.
Maekawa, Yasunari; Suzuki, Yasuyuki; Yoshida, Masaru; Maeyama, Katsuya*; Yonezawa, Noriyuki*
Polymer, 44(8), p.2307 - 2312, 2003/04
Times Cited Count：7 Percentile：28.98(Polymer Science)The preparation of ion track membranes of thermally stable polyimide films has been performed by ion beam irradiation of partially imidized polyamic acid (PAA) films followed by alkaline etching and final imidization. No discernible positive hole patterns were observed on the irradiated films of partially imidized PAA containing sulfonyl linkages, although sulfonyl group is known to be highly sensitive to ion beams. In contrast, positive hole patterns appeared on the irradiated films of the partially imidized PAA with 68-89% imidization degrees that contains sulfonyl linkages along with a methylene group in the main chain. The most contrasty hole patterns with 0.3 m diameter were observed on the irradiated PAA films of 89% imidization degree. The irradiated PAA film with the hole patterns was then transformed to the corresponding polyimide film with curing at 350
C for 1 h. From the structural comparison of the polyimides, the possible mechanism for the hole pattern formation is suggested.
Suzuki, Yasuyuki; Maekawa, Yasunari; Yoshida, Masaru; Maeyama, Katsuya*; Yonezawa, Noriyuki*
Chemistry of Materials, 14(10), p.4186 - 4191, 2002/10
Times Cited Count：17 Percentile：53.57(Chemistry, Physical)Dual tone imaging of polyimide films was prepared by Xe ion beam irradiation of partially imidized polyamic acid (PAA) films followed by alkaline etching in aqueous tetramethylammonium hydroxide solution and heating of treated films. In 87% imidized PAA film, ion beam irradiation produced a negative hemispheric structured image with 1.0 mm height and 1.5 mm diameter. In contrast, a positive hole pattern with 0.3 mm diameter appeared on the 82% imidized PAA film. Positive and negative images were considered to be switched by slight change in the balance of scission and crosslinking of the polymer chains, resulting from energy deposition of the ion beam.
Nucl.Tracks, 13(1-2), p.33 - 44, 1979/00
no abstracts in English
;
Science, 199(4327), p.421 - 422, 1978/00
Times Cited Count：14no abstracts in English
Koshikawa, Hiroshi; Yamamoto, Shunya; Sugimoto, Masaki; Kitamura, Akane; Sawada, Shinichi; Yamaki, Tetsuya
no journal, ,
Chemical etching of polymer films irradiated with heavy ions leads to the formation of ion-track membranes with nanoscale pores in different shapes. Particularly, conically-shaped pores are expected to have a potential to create metallic nanoneedles by combination of vapor-deposition and electroplating methods. In this study, we prepared copper nanoneedles inside the conical pores of polyimide (PI)-based ion-track membranes and investigated their morphology. The PI films were irradiated with 
Ar ions. The irradiated films were etched in a sodium hypochlorite solution at 60C for 0.5 h, leading to the formation of conical pores with a surface diameter of ca. 500 nm. A very thin Au layer was deposited on this pore side of the ion-track membranes; then, it was used as a cathode for electroplating copper into the pores. After dissolving the PI templates, we obtained the copper needles ca. 500 nm in base diameter and 1.2 m in height on copper plates.
