辐射交联制备改性CMC水凝胶的溶胀行为研究

SWELLING BEHAVIOR OF MODIFIED CMC HYDROGEL PREPARED BY RADIATION CROSSLINKING

利用丙烯酰胺 (AAm)接枝改性纤维素 ,然后进行羧甲基化反应得到高取代度的丙烯酰胺 羧甲基纤维素钠 (AAm CMC Na) .对该材料进行γ射线辐照制备出新型改性CMC水凝胶 .研究了这种水凝胶的溶胀动力学、交联动力学以及温度、pH值和无机盐浓度对水凝胶溶胀行为的影响 ,并与CMC Na水凝胶进行了比较 .结果表明 ,该水凝胶和CMC Na水凝胶相比 ,优点在于辐照交联所用的剂量下降 ,而且所需的CMC浓度减少 .AAm CMC Na水凝胶的溶胀度随温度升高而增大 ,在pH为 6～ 8范围内达到最大值 ,并随无机盐浓度与吸收剂量增加而下降 ,表现出较好的温度敏感性和pH敏感性 。

Carboxymethyl cellulose (CMC) is one of the most useful cellulose derivatives. However, it is difficult to obtain CMC with higher degree of substitution ( DS), and CMC with lower DS often exhibits a poor solubility, in water. In order to improve the degree of substitution of carboxymethyl cellulose, acrylic amide (AAm) was grafted onto cellulose, and the. sodium carboxymethyl cellulose with AAm groups (AAm-CMC-Na) was synthesized. In the present work, a novel modified CMC hydrogel based on AAm-CMC-Na aqueous solution was obtained by using gamma irradiation under appropriate conditions. The swelling behavior, crosslinking kinetics of AAm-CMC-Na hydrogels and the effects of temperature, pH value and inorganic salt concentration on the swelling ratio of hydrogel were studied in detail. Experimental. results showed that, when the concentration of AAm-CMC-Na aqueous solutions is above 12.5%, hydrogels could be prepared by gamma irradiation. However, comparing with radiation prepared CMC-Na hydrogels, the novel AAm-CMC-Na hydrogel could be produced at lower dose and lower concentration. Degradation is the predominant reaction in gamma irradiation for these two hydrogels. The swelling ratio of AAm-CMC-Na hydrogel in water. was improved with the increase of temperature and had a maximum value in the range of pH = 6 similar to 8, moreover, the swelling ratio decreased with the increasing of inorganic salt concentration and absorbed dose. The effect of CaCl(2) solution on swelling behavior of AAm-CMC-Na hydrogel was more remarkable than that of NaCl solution. The irradiation prepared AAm-CMC-Na hydrogels showed good sensibility to temperature and pH value, which implied this novel hydrogel is expected to be a water absorption material and water preserver.