新型聚丙烯酸水凝胶的自愈及其溶胀动力学

Self-healing and Swelling Kinetics of a New Polyacrylic Acid Hydrogels

以丙烯酸(AA)、水、七元瓜环(CB[7])和过硫酸钾(KPS)、NaCl为原料制备七元瓜环/聚丙烯酸水凝胶(CB[7]/PAA hydrogel),宏观观察了CB[7]/PAA hydrogel的自愈性,研究了这种自愈水凝胶的网络形成作用力。结果表明:这种水凝胶网络的形成作用力主要是多重氢键,具有自愈性,自愈后的最大拉伸量约为原长的1.73倍;AA含量较低时随着AA含量的提高溶胀率和溶胀速率增大,AA含量较高时随着AA含量的提高溶胀率和溶胀速率减小;这种水凝胶的溶胀率与溶胀速率,在p H值为7.6的水溶液中的值明显高于在p H值为10.0和4.0水溶液中的值。使用Non-Fickian扩散模型研究了CB[7]/PAA hydrogel的溶胀机理。CB[7]/PAA hydrogel的动力学指数n、凝胶速率常数K和水分子扩散系数D的值表明,这种水凝胶的溶胀符合Non-Fickian扩散模式,在溶胀初期水分子的扩散速率与凝胶中的链段松弛速率相当。

A self-healing CB[7]/PAA hydrogel was prepared with acrylic acid（AA）, H_2O, cucurbituril[7]（CB[7]）, potassium persulfate（KPS） and Na Cl as raw materials. The self-healing process of CB [7]/PAA hydrogel was investigated by means of FT-IR and1 H NMR techniques. Results show that the hydrogel networks formed during the self-healing of CB [7]/PAA hydrogel are mainly induced by the existence of multiple hydrogen bonds, and after the self-healing, the maximum tensile elongation of CB[7]/PAA hydrogel can reach about 1.73 times of that of the as prepared ones. Within a range of low AA content, the swelling and swelling rate of the hydrogel increase with the increasing AA content, while in a range of high AA content, the swelling and the swelling rate decreases with the increasing AA content; the swelling and swelling rate of the hydrogel in the aqueous solution of p H=7.6 were obviously higher than those in the aqueous solution of p H=10.0 and p H=4.0. The kinetic index n, rate constant K and water diffusion coefficient D of CB[7]/PAA hydrogel were acquired corresponding to non-Fickian diffusion mode. It follows that the swelling of CB [7]/PAA hydrogel is in accordance with the non-Fickian diffusion mode, and the diffusion rate of water molecules is comparable to that of the relaxation rate of chain segments in the hydrogel.