Observation of carboxymethyl cellulose radicals produced by OH radicals

Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*

Polysaccharide derivatives, for example carboxymethyl cellulose (CMC), at a concentrated aqueous solution form gels by irradiation. Radiation-crosslinking mechanism of polysaccharide derivatives is not well known, and polysaccharide radicals formed after ionizing irradiation have not been assigned clearly. The purpose of this study is to observe directly ESR spectrum of CMC radicals in an aqueous solution reacted with OH and to analyze radical sites of CMC radical in detail. It was succeeded to detect CMC radicals in an aqueous solution by ESR using OH radicals from photolysis of hydrogen peroxide (sample: CMC 10 mM / hydrogen peroxide 10 mM). It was identified that a radical on carboxymethyl group linked with C2 and C3 appears as doublet spectrum and that a radical on carboxymethyl group linked with C6 appears as triplet-doublet spectrum from study of hydrogen atom position around the radical and of hyperfine coupling constant.