多壁碳纳米管表面甘草酸分子印迹聚合物的制备及其应用

Preparation and Application of Glycyrrhizic Acid Imprinted Polymers Based on Multi-walled Carbon Nanotubes

目的:研制甘草酸为模板的固相萃取柱,并将其应用到药草中高纯度甘草酸的分离富集方面。方法:以丙烯酰胺修饰的碳纳米管为载体,甘草酸为模板,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,N,N-二甲基甲酰胺(DMF)为致孔剂,采用沉淀聚合技术,在碳纳米管表面成功接枝甘草酸印迹聚合材料。采用红外光谱、扫描电镜和热重分析对印迹材料的性能进行表征。结果:当功能单体为丙烯酰胺,沉淀聚合温度为60℃,致孔剂是DMF,EGDMA与溶剂比例为1∶20时,能够在在碳纳米管表面印迹一层稳定、均匀的印迹材料;Scatchard模型表明,多壁碳纳米管-分子印迹聚合物(MWCNTs-MIP)对甘草酸有着不同亲和力的2种结合位点,即高结合位点的平衡常数(Kd)1.17 mmol·L-1,最大表观吸附量(Qmax)741.5μg·g-1,低结合点的Kd 3.96 mmol·L-1,Qmax1 668.5μg·g-1,并且MWCNTs-MIP对甘草酸有特异性识别能力。结论:优化条件合成的分子印迹聚合物具有更好的形态结构,对目标分子具有很好的吸附效率,故作为固相萃取材料应用于药草中甘草酸的分离富集方面有一定研究价值。

Objective： To prepare the solid phase extraction column for the effective separation and enrichment of glycyrrhizic acid. Method： A novel surface molecularly imprinted polymer was synthesized,with acrylamide（ AM）-modified multi-walled carbon nanotubes（ MWCNTs） as supporting matrix,glycyrrhizic acid as template molecule,acrylamide（ AM） as functional monomer,N,N-dimethyl formamide（ DMF） as pore former and ethylene glycol dimethacrylate（ EGDMA） as cross-linking agent. The multi-walled carbon nanotubes molecularly imprinted polymers were characterized by FTIR,SEM and TGA. Result： A stable even layer was imprinted on the MWCNTs surface when the precipitation polymerization temperature was 60 ℃,the pore forming agent was DMF,EGDMA and solvent ratio was 1 ∶ 20. The Scatchard model shows that MWCNTs-molecularly imprinted polymers（ MIP） had two kinds of binding sites with different affinities and specific recognition ability of glycyrrhizic acid（ Kd 1. 17 mmol·L- 1,Qmax741. 5 μg·g- 1,Kd 3. 96 mmol·L- 1,Qmax1 668. 5 μg·g- 1）.Conclusion： The molecularly imprinted polymers synthesized with optimal conditions have a good morphological structure and adsorption efficiency,so these polymers as solid-phase extraction material have a certain research value in separation and enrichment of glycyrrhizic acid in medicinal herbs.