纤维素基水凝胶的溶胀动力学研究

Study on the Swelling Kinetics of pH-sensitive Cellulose-based Hydrogels

中文关键词:  pH值敏感性  溶胀动力学  水凝胶  纤维素

Key Words:pH-sensitive  swelling kinetic  hydrogels  cellulose

中文摘要:

      以纤维素为骨架，丙烯酸(AA)为单体，采用接枝共聚方法在85%磷酸溶液反应介质中合成了pH值敏感水凝胶(C-g-AA)。主要研究了C-g-AA水凝胶的pH值敏感性及在不同pH值溶液(pH值分别为1.15，6.86，11.05)中的溶胀可逆性和溶胀动力学行为，并与在去离子水中的溶胀行为进行对比。结果表明，C-g-AA水凝胶的溶胀比随着凝胶中AA组分的增加而增加，最高可达73%；水凝胶溶胀具有明显的pH值敏感性，当pH值＞7时达到溶胀平衡，水凝胶对pH值的溶胀可逆性良好；不同pH值溶液中的溶胀动力学表明，溶胀初期水分子在水凝胶中的扩散行为可用non-Fickian扩散定律来描述，整体溶胀行为满足Schott二级动力学方程，而在去离子水中，水凝胶溶胀初期的扩散特征指数同样保持稳定，但整体溶胀行为却不遵循Schott二级动力学方程。

Abstract:

      Cellulose-graft-acrylic acid (C-g-AA) hydrogels were prepared via graft polymerization in 85% phosphoric acid solution, the pH sensitivity and reversibility, salt sensitivity and swelling kinetics of the hydrogels were tested. The results showed that the hydrogels had obvious pH sensitivity, the swelling reached equilibrium when pH＞7, and the hydrogels also displayed excellent pH reversibility. The swelling ratio in distilled water was increased with increasing of AA components in hydrogels, and could reached 73% with mole ratio of 6∶1 (AA/cellulose). The swelling kinetics in the solutions with various pH values indicated that the initial water intake of hydrogels followed a non-Fickian type diffusion with the diffusion exponents all higher than 0.5, and the whole swelling process fit the Schott model well. In distilled water, the initial water intake also followed a non-Fickian type diffusion, while the whole swelling did not obey the Schott swelling kinetic model.