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Optical Properties of ZnO Nanoparticles Capped with Polymers
Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
* Author to whom correspondence should be addressed.
Received: 14 May 2011; Accepted: 16 June 2011 / Published: 17 June 2011
Abstract: Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging
Keywords: nanoparticle; fluorescence; capping; zinc oxide; polyethylene glycol; polyvinyl pyrrolidone
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MDPI and ACS Style
Tachikawa, S.; Noguchi, A.; Tsuge, T.; Hara, M.; Odawara, O.; Wada, H. Optical Properties of ZnO Nanoparticles Capped with Polymers. Materials 2011, 4, 1132-1143.
Tachikawa S, Noguchi A, Tsuge T, Hara M, Odawara O, Wada H. Optical Properties of ZnO Nanoparticles Capped with Polymers. Materials. 2011; 4(6):1132-1143.
Tachikawa, Shingo; Noguchi, Atsushi; Tsuge, Takeharu; Hara, Masahiko; Odawara, Osamu; Wada, Hiroyuki. 2011. "Optical Properties of ZnO Nanoparticles Capped with Polymers." Materials 4, no. 6: 1132-1143.