Synthesis of microscopic carboxymethylcellulose hydrogels with metal ions by radiation-induced crosslinking

放射線橋かけによる金属イオン含有カルボキシメチルセルロース微小ハイドロゲルの合成

長澤 尚胤; Rokita, B.*; Ulanski, P.*; 廣木 章博; Rosiak, J. M.*; 田口 光正; 玉田 正男

Nagasawa, Naotsugu; Rokita, B.*; Ulanski, P.*; Hiroki, Akihiro; Rosiak, J. M.*; Taguchi, Mitsumasa; Tamada, Masao

化学修飾された水溶性のセルロース誘導体であるカルボキシメチルセルロース(CMC)は、塩化カルシウムや塩化マグネシウム等の金属塩と錯体を形成して凝集する性質を有している。CMCの放射線橋かけ技術に、金属塩との凝集作用等を組合せて、橋かけ初期過程における微小ゲル形成挙動について検討した。0.1%CMC水溶液に、塩化カルシウムをCMC糖残基に対してモル比で0.5から1.25の範囲で添加して50kGyまで線を照射すると、CMC鎖の初期平均粒径が800nmから50nmまで粒径が減少することを観測し、ナノ、マイクロメーターサイズゲルを生成できる技術に見通しを得た。

The chemically modified polysaccharide derivatives such as carboxymethylcellulose (CMC) are soluble in water so that have been widely used in many industrial applications. Recently, the idea of synthesis of CMC microscopic gels by means of ionizing radiation has been appeared. To obtain microscopic gels with given molecular weights and sizes the selection of proper experimental conditions should be done. However, in case of diluted CMC aqueous solutions during irradiation, the degradation is the dominant process. In order to solve this problem, we investigated a new method by adding metal ions (CaCl) to CMC solution before irradiation. The Ca ions reduce interaction of the charge for CMC molecules and makes coils structure. Therefore, macroradicals formed on such the coiled polymer chains can make possible formation of inter- and intra-molecular crosslinking. Formation of microscopic gels in this system was observed. For 0.1% CMC with CaCl at molar ratio CMC:CaCl 1:0.5-1.25 during irradiation up to 50 kGy, the increment of Ca ions and dose decrease the particle sizes from 800 nm to 50 nm. The combination of metal ions addition and radiation-induced crosslinking caused significant synthesis of nano- and micro-meter sized carboxymethylcellulose hydrogels.