GA-g-PAA/ST复合水凝胶的合成与表征

Synthesis and Characterization of a GA-g-PAA/ST Composite Hydrogel

以阿拉伯胶(GA)、丙烯酸(AA)、海泡石黏土(ST)为原料,采用微波辐射法,通过接枝共聚合成了GA-g-PAA/ST复合水凝胶,利用FTIR、XRD和SEM表征了水凝胶的结构和形貌,用TG分析了水凝胶的热稳定性能,同时探讨了水凝胶在不同价态阳离子盐溶液的溶胀行为和保水性能。结果显示:GA、ST和AA发生了接枝共聚反应,共聚物插层到ST的层间,形成剥离型均匀的三维网络复合高吸水性水凝胶。当盐溶液浓度为20 mmol/L时,水凝胶在NaCl、BaCl_2、AlCl_3溶液中的吸水倍率分别为112、38和29 g/g。表面活性剂溶液浓度为20 mmol/L时,水凝胶在十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)溶液的吸水倍率分别为135和105 g/g。水凝胶在NaCl和BaCl_2溶液经过3次溶胀-去溶胀循环后,其吸水倍率分别为80和12 g/g,表明水凝胶在NaCl和BaCl_2盐溶液中具有较强的盐响应性能和良好的可逆行为,水凝胶具有较好的热稳定性和保水性能。

A novel GA-g-PAA/ST composite hydrogel was prepared by graft copolymerization of gum arabic(GA), acrylic acid(AA), and sepiolite clay(ST) under microwave irradiation. The structure and morphology of GA-g-PAA/ST composite hydrogel were characterized by FTIR, XRD and SEM. The thermal stability of the hydrogel was analyzed by TG. The swelling behavior and water retention of the hydrogel in different cationic salt solutions were also discussed. The results showed that the graft copolymerization reaction of GA, ST, and AA took place, and the copolymer intercalated into the interlayer of ST to form a delaminated three-dimensional network composite hydrogel. When the concentration of salt solution was 20 mmol/L, the absorbency of GA-g-PAA/ST in NaCl solution, BaCl2 solution, and AlCl3 solution was 112, 38 and 29 g/g, respectively. The absorbency of GA-g-PAA/ST in 20 mmol/L sodium dodecyl sulfate(SDS) solution and 20 mmol/L hexadecyl trimethyl ammonium bromide(CTAB) solution was 135 and 105 g/g, respectively. After repeating three cycles of swelling and deswelling by a solution of NaCl and BaCl2, the absorbency of the hydrogel was 80 and 12 g/g, respectively, indicating that the hydrogel had strong salt responsive property and good reversible behavior in the solution of NaCl and BaCl2. The hydrogel had good thermal stability and water retention capacity.