表面活性剂对疏水缔合水凝胶性能的影响

IMPACT OF SURFACTANT ON THE PROPERTIES OF THE HYDROPHOBICALLY ASSOCIATING HYDROGELS

通过丙烯酰胺(AM)和丙烯酰胺基十八羧酸钠(NaAAS)共聚合,在没有任何外加化学交联剂的情况下,分别在水溶液和十二烷基硫酸钠(SDS)溶液中通过自由基聚合制备了疏水缔合水凝胶,命名为HA凝胶和SHA凝胶.系统研究HA凝胶和SHA凝胶的机械拉伸性能发现,调节AM和NaAAS的含量,可以使SHA凝胶具有相较不含SDS的HA凝胶更好的力学拉伸性能.HA凝胶在水中不溶解且在纯化和溶胀过程中几乎没有损失,而SHA凝胶体系中的SDS可以扩散出凝胶网络溶解到水中,使得SHA凝胶表现出更加明显的溶胀-去溶胀-平衡溶胀行为;在盐水中由于疏水缔合得到加强,HA凝胶和SHA凝胶都表现出化学凝胶的溶胀特点.在常温下HA凝胶不能实现自愈合,而SHA凝胶具有较好的自愈合能力,并且自愈合效果可以通过SHA凝胶中SDS和聚合物固含量调节.

The hydrophobically associating hydrogels,namely HA gels and SHA gels,were prepared by free radical copolymerization of acrylamide(AM) and sodium 9 or 10-acrylamidostearic acid(NaAAS) in pure water and in aqueous solution of sodium dodecyl sulphate(SDS),respectively,without any chemical crosslinkers.The mechanical properties of HA gels and SHA gels were systematic investigated by one-way tensile experiments,and the results confirmed the high toughness of the as-obtained hydrogels.Further more,by adjusting the AM and NaAAS contents,the SHA gels could exhibit ultrahigh toughness compared to the HA gels without SDS.The swelling behaviors of HA and SHA gels in aqueous solutions and in 0.1 mol/L NaCl were studied,respectively.The HA gels were not soluble in water,and almost no weight loss was detected during the purification and swelling processes.However,SDS could escape from the hydrogel networks into water,leading to the unique process of swelling-deswelling-swelling equilibrium;in brine,both of the HA gel and SHA gel show the swelling curves just like those of chemical cross-linked hydrogels because the hydrophobically association strength of the physical cross-linked units are strengthened by introduction of NaCl.Moreover,the HA gels couldn't heal themselves at room temperature.However,the SHA gels exhibited well self-healing ability,and the self-healing effect could be improved by adjusting the SDS and polymer contents.