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Photosensitized Reaction of Poly(L-lactic Acid) via Two-Photon Ionization of Dopant

Published online by Cambridge University Press:  15 March 2011

Wataru Sakai ,
Kosuke Wakabayashi ,
Hiroshi Nishinaka ,
Hiroki Kawamoto ,
Motoi Kinoshita  and
Naoto Tsutsumi
Wataru Sakai
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
Kosuke Wakabayashi
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
Hiroshi Nishinaka
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
Hiroki Kawamoto
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
Motoi Kinoshita
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
Naoto Tsutsumi
Affiliation:
Department of Polymer Science & Engineering, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto 606-8585, JAPAN
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Abstract

We here studied photosensitized radical reaction of poly(L-lactic acid) (PLA) using spectrophotometry, electron spin resonance (ESR), gel permeation chromatography (GPC) measurements, and semiempirical molecular orbital calculation. PLA doped with N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was irradiated at 77 K using UV light. After the irradiation, we observed a new broad absorption band that is assigned to TMPD radical cation produced by two-photon ionization. ESR spectrum of the irradiated sample also indicated presence of main chain scission radical of PLA as well as the TMPD radical cation. By increasing the irradiation time, the ESR spectrum changed by another radical species which is produced by dehydrogenation of PLA main chain. Spectral simulation for the obtained ESR spectra revealed changes of relative amounts. The GPC measurements clearly indicated decrease in molecular weight of PLA after the irradiation. The semiempirical molecular orbital calculation was used to confirm the reaction scheme of radical anion decomposition.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 708: Symposium BB – Organic Optoelectronic Materials, Processing and Devices , 2001 , BB3.9
Copyright
Copyright © Materials Research Society 2002

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References

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