基于柱[5]芳烃聚合物水凝胶的制备及对百草枯的可视化检测

Construction of Pillar[5]arene-functionalized Polymeric Hydrogel and Its Visual Detection of Herbicide Paraquat

合成了单功能化的柱[5]芳烃单烯体,然后将其与丙烯酰胺(AAM)、交联剂N,N'-亚甲基双丙烯酰胺(MBA)和引发剂偶氮二异丁腈(AIBN)在70 oC下反应12 h后形成含有大环主体柱[5]芳烃的高分子聚合物,将此聚合物分别浸泡于DMSO、水中各1周,并每天更换新鲜的溶剂,最后通过此聚合物的红外光谱图证实成功制备了含有柱[5]芳烃的聚合物水凝胶.利用紫外吸收光谱测试表征了水凝胶对百草枯的吸收作用.将该水凝胶浸入浓度从小到大的百草枯溶液中,发现水凝胶颜色由浅黄色变为棕红色,这是由于水凝胶中的柱[5]芳烃与N,N'-二甲基-4,4'-联吡啶客体分子之间主客体作用形成了含有准轮烷结构的超分子聚合物所致.

A mono-functionalized pallar[5]arene was designed and synthesized. It was then mixed with AAM, MBA, and AIBN in DMSO. The mixture was stirred at 70℃ for 12 h to give a functionalized polymer of pillar[5]arene. The polymer was then immersed in DMSO and deionized water, respectively, and the polymeric hydrogel was successfully prepared. For the synthesis of the polymer hydrogels with expected morphology and mechanical property, the best molar ratio was found to be 1：9：0.054：0.25 for functionalized pallar[5]arene monomer：AAM：MBA：AIBN was, and the polymerization reaction was at 70 ℃ for 12 h after the mixture deoxygenized. While the above optimized polymeric hydrogel was immersed in paraquat aqueous solution, a supramolecular polymeric hydrogel was achieved due to the host-guest complexing of paraquat in aqueous soltuion with pillar[5]arene moiety in the hydrogel. And the strong host-guest interaction of pillar[5]arene with paraquat was attributed to charge-transfer interactions between the electron-rich and suitable size of cavities of the pillar[5]arene derivatives and the encircled electron-poor guests. It was found that, during the formaiton of the supramolecular polymeric hydrogel, the color of the hydrogel became deep brown from pale yellow with increasing concentration of paraquat, which provided a good method for the collection and visual detection of paraquat in the aqueous solution by naked eyes. Increasing temperature promoted the absorption of paraquat by the polymeric hydrogel as well. In addition, the detection of paraquat by such polymeric hydrogel was studied by UV-Vis spectroscopy and UV-Vis absorption showed that the concentration of paraquat in water was decreasing because of its absorption by the polymeric hydrogel. This new type of pillararene-based adsorbent materials is considered as a potential adsorbent for the removal of harmful substances from wastewaters.