Real time measurement of photochemical surface reactions by using a total reflection prism
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0890-Y08-09.1
Real time measurement of photochemical surface reactions by using a total reflection prism
Yuki Sato1 , Yuji Sato2 , and Masataka Murahara2 1 Department of Electrical and Electronics Engineering, Tokai University 1117 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan 2 Entropia Laser Initiative, Tokyo Institute of Technology 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552, Japan ABSTRACT The photochemical reaction processes, i.e., photo-dissociation of a reaction solution, defluorination of fluorocarbon [FEP], and substitution of a hydrophilic group, were measured in real time, when irradiating a Xe2 excimer lamplight on the water or ammonia solution as a reaction solution and FEP placed on the attenuated total reflectance [ATR] prism. In case of ammonia solution, with the increase in irradiation time, the absorption peaks of 3300 cm-1 and 1650 cm-1 gradually decreased, and the new absorption of -CF2 -NH2 gradually appeared at 1410 cm-1 , which presented the strongest absorption after UV irradiation for 25 minutes. The results indicate that the ammonia water has turned to amino groups. In addition, the contact angle of water was measured. When compared to the untreated sample, whose contact angle was 110 degrees, the contact angle of the sample treated with water became 31 degrees after the Xe2 lamp irradiation for 25 minutes, and that of the sample modified by ammonia water further improved to 27 degrees after the irradiation for 25 minutes.
INTRODUCTION A number of surface modification studies are done for giving functions for particular purposes to high-polymer materials. These surface modifications are a wet-process and a dry-process. In wet-process, Nelson et al. modified the wettability of a polytetrafluoroethylene [PTFE] by soaking in the mixed solution of metal sodium and liquid ammonia for improving an epoxy resin adsorption [1]. In dry-process, Nakao et al. analyzed the polystyrene that had been irradiated Ne- ion beam by X-ray photoelectron spectroscopy [XPS]. The results showed that the benze ne ring of the polystyrene surface was destroyed and new C-O and C=O were composed [2]. Park et al. modified the FEP surface into hydrophilic by using H2 , Ar, N2 , and O2 plasma methods, and improved the adhesion to copper [3]. Fakes et al. analyzed the PMMA surface modified with plasma by XPS and measuring the contact angle, and reported that the C-H of PMMA surface decreased with plasma irradiation, whereas the C-O and C=O increased, and the depth was at least 20 nm [4]. The method of analysis for before and after treatments enabled to investigate the movement of surface atoms and molecule s. But, in the XPS analysis, it is difficult to analyze the surface modification process because it requires capturing a charged particle as a signal and keeping at a high vacuum. The sample of before and after treatments
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was also analyzed by FT-IR; however, there is no previous report on the measurement of surface modification process. The reaction mechanism is still a matter of conjecture. Thu
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