计算机辅助三聚氰胺分子印迹聚合物的制备

Preparation of Melamine Molecular Imprinted Polymer by Computer Aided Design

以三聚氰胺(MAM)为印迹分子,丙烯酰胺(AM)、甲基丙烯酸(MAA)、N,N-亚甲基双丙烯酰胺(MBA)和衣康酸(IA)为功能单体,二乙烯基苯(DVB)、乙二醇双甲基丙烯酸酯(EGDMA)和三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,采用量子化学密度泛函理论的长程校正方法模拟并探讨了MAM与4种功能单体的成键作用位点、成键数目、印迹反应摩尔比及印迹作用机理.依据结合能(ΔE)优化了功能单体和交联剂,并借助分子中原子理论(AIM)揭示了MAM与功能单体印迹作用的本质.计算结果表明,MAM通过氢键与4种功能单体以摩尔比1∶6进行印迹聚合,其中IA与MAM形成的复合物结合能最低,结构最稳定;与TRIM和EGDMA交联剂相比,DVB与MAM结合能最低,更适合作为MAM-IA印迹聚合物的交联剂.采用沉淀聚合法合成MAM分子印迹聚合物(MAM-MIPs)并测定其吸附性,当MAM与IA印迹摩尔反应比为1∶6时,以DVB为交联剂时制备的MAM-MIPs吸附性最好,其微球平均粒径为195 nm;Scatchard分析结果表明,在所研究的浓度范围内MIPs对印迹分子MAM的结合位点是等价的,其最大表观吸附量Qmax为20.79mg/g,离解平衡常数Kd为58.82 mg/L;与环丙氨嗪(CYR)、三聚氰酸(CYA)和三聚硫氰酸(TRI)在牛奶中的吸附量相比,MAM-MIPs对MAM表现出较强的特异吸附能力.

Melamine（MAM） was chosen as the template molecule and acrylamide（AM）,methacrylic acid（MAA）,N,N＇-methylenebisacrylamide（MBA）,itaconic acid（IA） were as the function monomers,the ethylene glycol dimethacrylate（EGDMA）,trimethacrylate（TRIM）,and divinylbenzene（DVB） were as the cross-linking agents,respectively.Long-range correction method of quantum chemistry density functional theory was used to simulate and discuss the bonding site,the number of hydrogen bonds,imprinted ratio of the stable complex,and the reaction mechanism.The optimizations of function monomers and the cross-linking agents were according to the bond energy（ΔE）.The nature of the imprinting effect was also studied by the atoms in molecules（AIM） theory.The results indicate that MAM and the four monomers have interaction to form imprinted polymers via the hydrogen bonds,and the molar ratio is 1 ∶ 6.The MIPs synthesized using IA as monomer owns the lowest bond energy,and the complex configuration is the most stable.The DVB as crosslinking agent with the highest binding energy in comparison with the TRIM and EGDMA is the best one for MAM-MIPs.In addition,the MAM-MIPs were prepared by precipitation polymerization to study the adsorption capacity characteristics.The results show that the MAM-MIPs（molar ratio = 1 ∶ 6） synthesized with IA as monomer and DVB as cross-linking agent have the best binding capacity.The average diameter of MAM-MIPs is 195 nm.The analysis of the Scatchard plot reveals that the binding sites of MAM-MIPs to MAM are equal class under the studied concentration range,the apparent maximum adsorption quantity（Qmax） is 20.79 mg /g,the dissociation constant（Kd） is 58.82 mg /L.The adsorption quantity of MIPs to MAM is obviously higher than that of cyromazine（CYR）,cyanuric acid（CYA）,and trithiocyanuric（TRI） in milk,which shows better specific absorption capacity.The studies can provide theoretical and experimental basis for screen of the functional monomer,the imprinting ratio,and cross-linking agent for the preparation of MAM-MIPs.