title: Radiation-Induced Chemical Reactions in Hydrogel of Hydroxypropyl Cellulose (HPC): A Pulse Radiolysis Study.
abstract: We performed studies on pulse radiolysis of highly transparent and shape-stable hydrogels of hydroxypropyl cellulose (HPC) that were prepared using a radiation-crosslinking technique. Several fundamental aspects of radiation-induced chemical reactions in the hydrogels were investigated. With radiation doses less than 1 kGy, degradation of the HPC matrix was not observed. The rate constants of the HPC composing the matrix, with two water decomposition radicals [hydroxyl radical (•OH) and hydrated electron ([Formula: see text])] in the gels, were determined to be 4.5 × 109and 1.8 × 107M-1s-1, respectively. Direct ionization of HPC in the matrix slightly increased the initial yield of [Formula: see text], but the additionally produced amount of [Formula: see text] disappeared immediately within 200 ps, indicating fast recombination of [Formula: see text] with hole radicals on HPC or on surrounding hydration water molecules. Reactions of [Formula: see text] with nitrous oxide (N2O) and nitromethane (CH3NO2) were also examined. Decay of [Formula: see text] due to scavenging by N2O and CH3NO2were both slower in hydrogels than in aqueous solutions, showing slower diffusions of the reactants in the gel matrix. The degree of decrease in the decay rate was more effective for N2O than for CH3NO2, revealing lower solubility of N2O in gel than in water. It is known that in viscous solvents, such as ethylene glycol, CH3NO2exhibits a transient effect, which is a fast reaction over the contact distance of reactants and occurs without diffusions of reactants. However, such an effect was not observed in the hydrogel used in the current study. In addition, the initial yield of [Formula: see text], which is affected by the amount of the scavenged precursor of [Formula: see text], in hydrogel containing N2O was slightly higher than that in water containing N2O, and the same tendency was found for CH3NO2.
authors.affiliation: a   Nuclear Professional School, School of Engineering, The University of Tokyo, Shirakata-shirane 2-22, Tokai-mura, Naka-gun, Ibaraki, 319-1188 Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamashita
authors.affiliation: b   Laboratoire de Chimie Physique/ELYSE, UMR 8000 CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay Cedex, France.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: b   Laboratoire de Chimie Physique/ELYSE, UMR 8000 CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay Cedex, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Marignier
authors.affiliation: c   Department of Advanced Functional Materials Research, Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), 1233 Watanuki-machi, Takasaki, Gunma 370-1292, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hiroki
authors.affiliation: c   Department of Advanced Functional Materials Research, Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), 1233 Watanuki-machi, Takasaki, Gunma 370-1292, Japan.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Taguchi
authors.affiliation: b   Laboratoire de Chimie Physique/ELYSE, UMR 8000 CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay Cedex, France.
authors.forename: Mehran
authors.initials: M
authors.lastname: Mostafavi
authors.affiliation: a   Nuclear Professional School, School of Engineering, The University of Tokyo, Shirakata-shirane 2-22, Tokai-mura, Naka-gun, Ibaraki, 319-1188 Japan.|d   Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656 Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Katsumura
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D007700:Kinetics; D011675:Pulse Radiolysis; D014867:Water / Q000737:chemistry
chemical_list: D020100:Hydrogels; D014867:Water; D002482:Cellulose; C008079:hydroxypropylcellulose