沉淀聚合法制备三聚氰胺分子印迹聚合物微球

以三聚氰胺为模板分子,以甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在乙腈-乙二醇(20∶1,V/V)混合溶剂中沉淀聚合制备了分子印迹聚合物微球.利用1H-NMR和紫外光谱方法研究了模板与功能单体相互作用情况.结果表明,三聚氰胺与甲基丙烯酸(MAA)分子通过协同氢键作用形成1∶2型氢键配合物.利用扫描电镜和红外光谱对聚合物微球的结构进行了表征.结果表明,印迹聚合物近似圆球形,粒径约为400～500 nm,且大于非印迹聚合物微球,表面存在大量的结合位点.通过静态平衡吸附实验研究了聚合物微球对模板分子的结合能力,印迹聚合物微球在4 h后逐渐达到吸附平衡,Scatchard分析表明,印迹聚合物微球主要存在两类不同的结合位点,最大表观结合量(Qmax)和平衡离解常数(Kd)分别为Qmax1=22.97μmol/g,Kd1=0.14×10-3 mol/L;Qmax2=157.65μmol/g,Kd2=2.55×10-3 mol/L,计算得出表观印迹效率和有效印迹效率分别为68%和58%.此方法合成的印迹聚合物微球对三聚氰胺有较好的结合性能,可应用于三聚氰胺的分离检测.

PREPARATION OF MELAMINE MOLECULARLY IMPRINTED POLYMER MICROSPHERES BY PRECIPITATION POLYMERIZATION

Uniform molecularly imprinted polymer(MIP) microspheres were prepared by precipitation polymerization of methacrylic acid(MAA) and ethylene glycol dimethacrylate(EGDMA) using melamine as template in acetonitrile-ethylene glycol mixed solvent(20 ∶ 1,V /V).1H-NMR and UV spectrometry were employed to demonstrate the mechanism of the interaction between melamine and MAA,and the structure of the polymer microspheres was characterized by scanning electron microscopic(SEM) photographs and IR spectrometry.The results showed that the melamine-MAA complexes of 1 ∶ 2 mole ratio were obtained by cooperative hydrogen bonding.The MIP particles with many binding abilities on their surface were micro-spheres and the diameters ranging from 400 nm to 500 nm were larger than those of the non-imprinted polymer microspheres.The adsorption efficiency was investigated by equilibrium adsorption experiments.The data obtained showed that the imprinted polymer microspheres reached equilibrium after 4 h and had higher adsorption efficiency compared to the non-imprinted polymer microspheres,which had the same chemical composition.Scatchard plot’s analysis revealed that the apparent maximum binding capacity and the dissociation contents were Qmax1 = 22.97 μmol /g,Kd1 = 0.14 × 10-3mol /L for high affinity binding sites and Qmax2 = 157.65 μmol /g,Kd2 = 2.55 × 10-3 mol /L for low affinity binding sites,respectively.Thus,the apparent imprinting efficiency and the effective imprinting efficiency were calculated to be 68% and 58%,respectively.The melamine imprinted polymer microspheres synthesised in this method had better performance and could be used for separation,enrichment and analysis of melamine.