Free volume study of sulfonated FEP proton exchange membrane

Oka, Toshitaka; Oshima, Akihiro*; Washio, Masakazu*

Radiation Physics and Chemistry, 215, p.111364_1 - 111364_4, 2024/02

https://doi.org/10.1016/j.radphyschem.2023.111364

The polymer electrolyte fuel cell (PEFC) is a promising electrochemical device to produce power through hydrogen and oxygen reaction. It has been expected as a leading future clean power source for a vehicle and a residential power generation. Proton exchange membrane (PEM) is a key material for the performance and the cost of PEFC, development of a high performance and a low-cost PEM is required. Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) was irradiated by an electron beam under oxygen-free atmosphere at 25C, grafted with styrene in liquid phase at 80, and then sulfonated with a mixture of chlorosulfonic acid in carbon-tetrachloride at 25 for 24 h. The free volume size and the o-Ps annihilation probability were affected by not only the amount of the grafted styrene but also the sulfonic acid group.

Energy dissipation of para-positronium in polymers and silica glass

Kobayashi, Yoshinori*; Sato, Kiminori*; Yamawaki, Masato*; Michishio, Koji*; Oka, Toshitaka; Washio, Masakazu*

Applied Physics Express, 15(7), p.076001_1 - 076001_4, 2022/07

https://doi.org/10.35848/1882-0786/ac7c54

We discuss the energy dissipation of short-lived -positronium (-Ps) in polymers and silica glass. The parameter characterizing the Doppler broadening of -Ps annihilation is determined from the previously reported systematic data of positron annihilation age momentum correlation for various polymers and silica glass. A comparison of the parameter with that expected for thermalized -Ps trapped in a free volume reveals that -Ps is not thermalized and possesses excess energy in fluorinated polymers and silica glass, indicating that it is difficult for Ps to lose energy in substances containing heavy elements such as fluorine and silicon.

Evaluation of resist sensitivity for X-ray microscopy

Washio, Masakazu*; Oyama, Tomoko

O plus E, 36(3), p.272 - 275, 2014/03

no abstracts in English

Micro/nanofabrication of poly(-lactic acid) using focused ion beam direct etching

Oyama, Tomoko; Hinata, Toru*; Nagasawa, Naotsugu; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*; Taguchi, Mitsumasa

Applied Physics Letters, 103(16), p.163105_1 - 163105_4, 2013/10

https://doi.org/10.1063/1.4825277

Micro/nanofabrication of biocompatible and biodegradable poly(-lactic acid) (PLLA) was evaluated using focused Ga ion beam direct etching. The fabrication performance was determined with different ion fluences and fluxes. It was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat because the resistance of PLLA to thermal deformation is decreased when above its glass transition temperature (approximately 60C). By controlling the irradiation conditions, controlled micro/nanostructures of PLLA were fabricated, such as holes (80 nm) and alphabets (width: 100 nm). Moreover, focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds expected to have good cell attachment properties.

Micro-/nanofabrication of cross-linked poly(-lactic acid) using electron beam nanoimprint lithography

Okubo, Satoshi*; Nagasawa, Naotsugu; Kobayashi, Akinobu*; Oyama, Tomoko*; Taguchi, Mitsumasa; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Applied Physics Express, 5(2), p.027303_1 - 027303_3, 2012/02

https://doi.org/10.1143/APEX.5.027303

Electron beam nanoimprint lithography was proposed for fabricating the micro-/nanostructures of cross-linked poly(-lactic acid) (RX-PLLA). PLLA with triallyl isocyanurate (TAIC) solutions were dropped on the Si-molds fabricated by the conventional EB lithography technique. PLLA/TAIC on Si-molds were imprinted and cross-linked with doses from 10 to 500 kGy at room temperature under vacuum. The micro-/nanostructures of RX-PLLA were successfully obtained with high accuracy. Hence, it was found that the imprinted structures of RX-PLLA (100 kGy irradiation) show low line edge roughness and high thermal durability at 120 C.

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)

Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*

Radiation Physics and Chemistry, 80(2), p.264 - 267, 2011/02

https://doi.org/10.1016/j.radphyschem.2010.07.044

High linear energy transfer (LET) heavy ion beams were irradiated to poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth was precisely evaluated by analyzing each one of the films of the irradiation samples which were made of stacked ETFE films. It was indicated that conjugated double bonds would be generated by heavy ion beam irradiation, and their amounts should show the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for irradiation samples in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.

Micro-fabrication of biodegradable polymers using focused ion beam

Okubo, Satoshi*; Takahashi, Tomohiro*; Takasawa, Yuya*; Gowa, Tomoko*; Sasaki, Takashi*; Nagasawa, Naotsugu; Tamada, Masao; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Journal of Photopolymer Science and Technology, 23(3), p.393 - 397, 2010/11

https://doi.org/10.2494/photopolymer.23.393

Microfabrication of biodegradable polymers such as poly(butylene succinate--adipate) (PBSA) and poly(-caprolactone) (PCL) were demonstrated using focused ion beam (FIB) with maskless direct etching. As the result, the micro structures of PBSA and PCL were obtained. The etching depth of both PBSA and PCL were increased with increasing FIB fluence, and the etching rates were estimated to be about 1.3 10 m/(ions cm) and 1.2 10 m/(ions cm), respectively. Moreover, very thin films of PBSA and PCL were made by spin-coating method. The thicknesses of the spin-coated samples were about 200 nm, and the surface roughness was less than 10 nm (RMS). The fine structures such as micro-gear of PBSA and PCL were obtained without solid debris. The line width of the fabricated structure was about 250 nm.

Application of electron beams for the treatment of VOC streams

Hirota, Koichi; Sakai, Hiroki*; Washio, Masakazu*; Kojima, Takuji

Industrial & Engineering Chemistry Research, 43(5), p.1185 - 1191, 2004/03

https://doi.org/10.1021/ie0340746

Twenty volatile organic compounds (VOCs) were irradiated with electron beams in laboratory scale to obtain an electron-beam energy required for a 90% treatment. The experiments showed that the energy was related with the chemical structure and roughly estimated from rate constants for reactions with OH radicals. The cost analysis revealed that the unification of a self-shielding electron accelerator with a reactor could reduce the capital cost for an electron-beam system. Electron-beam technology is a promising method for the treatment of VOCs.

Development of high duty operation RF photoinjector

*; Kotaki, Hideyuki; Nakajima, Kazuhisa*; Kando, Masaki*; Kondo, Shuji; Dewa, Hidenori*; Watanabe, Takahiro*; Ueda, Toru*; Yoshii, Koji*; Kinoshita, Kenichi*; et al.

Proc. of 11th Symp. on Accelerator Sci. and Technol., p.473 - 475, 1997/00

no abstracts in English

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)

Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*

no journal, ,