【作者】 李颖；

【导师】 韩喜江； 李欣；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2010， 博士

【摘要】 分子印迹技术是制备对目标分子具有专一识别性能的高分子合成技术,其核心是分子印迹聚合物。分子印迹聚合物具有预定性、识别性、选择性等三大特性。本项研究将分子印迹技术与可逆加成-断裂链转移聚合方法相结合,在球形硅胶、磁性硅球、磁性荧光硅球及氧化石墨烯等不同载体表面接枝分子印迹聚合物膜,合成了具有强磁响应性、荧光性和高传质速率等性能的多功能分子印迹聚合物。通过透射电子显微镜、扫描电子显微镜、荧光显微镜、傅立叶红外光谱仪、振动样品磁强计、热重分析仪和比表面分析仪等对各种功能性分子印迹聚合物进行了结构分析表征,并研究了它们对水环境中内分泌干扰物的去除与识别机制。以球形硅胶为载体,制备了表面具有纳米结构的“核-壳”式分子印迹聚合物微球。吸附实验结果表明:吸附符合动力学二级反应模型,吸附规律较好的符合Langmuir吸附等温式;所制备的印迹聚合物微球对模板分子表现出了较强的亲和力和较优的选择性。通过密度泛函理论模拟计算,对分子印迹聚合物微球的选择性识别机制进行了理论分析。以磁性硅球为载体,制备了磁性分子印迹聚合物微球。该微球表面分子印迹聚合物膜的厚度约为22nm。所制备的磁性印迹聚合物微球对模板分子具有较强的吸附结合能力和优异的分子选择识别性能,重复使用五次依然表现出较好的亲和力和选择性。产物所具有的磁响应性(Ms=0.41eum/g)能够使其在外加磁场作用下,快速地从样品中分离出来。以磁性荧光硅球为载体,制备了磁性荧光分子印迹聚合物微球,该微球表现出磁响应性、荧光性能和热稳定性。微球中荧光层的厚度约为8.7nm,表面分子印迹聚合物膜厚度约为5.7nm。采用荧光分析法可使模板分子的检测限达到0.19μmol/L,该微球重复使用五次后依然具有较好的荧光强度和磁性能。此外,根据Stem-volmer方程分析了产物的荧光减弱过程属于静态淬灭机理。以氧化石墨烯为载体,制备了氧化石墨烯基分子印迹聚合物复合材料。该复合材料中表面分子印迹聚合物膜的厚度约为3.707nm。吸附实验结果表明:制备的复合材料对模板分子表现出更高的结合能力和更优的选择性,同时它还具有很好的可重复利用性。密度泛函理论计算揭示了石墨烯基材料为模板分子提供大的π表面,与模板分子形成π-π共轭作用使体系稳定,显著改善了分子印迹聚合物性能。更多还原

【Abstract】 Molecular imprinting is a highly accepted synthesis approach for the preparation of tailor-made recognition material with cavities that are able to selectively recognize target molecules. The molecular imprinted polymers boast the characters of prearrangement, recognition and selectivity. In this work, we have prepared multifunctional molecularly imprinted polymers with superparamagnetism, excellent fluorescent properties and fast transportation rate on different supportings such as silica gels, Fe3O4 functionalized silica gels, magnetic/optical silica gels and graphene oxide by combining reversible addition-fragmentation chain transfer (RAFT) polymerization approach and molecular imprinting technology. The resulting composites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) photoluminescence (PL) spectra, fourier transform infrared (FT-IR) analysis, vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and BET adsorption isotherm analysis. The mechanism of their selectivity for EDCs in water was also investigated.The super-thin surface-imprinted core-shell magnetic molecular imprinted nanobeads were prepared with spherical silica as the support. Absorption experiments demonstrated linearized pseudo second-order kinetic model, in good agreement with Langmuir absorption isotherm. The imprinted nanobeads showed strong affinity and excellent selectivity. Density functional theory calculations verified the mechanism of selectivity and recognition of these imprinted nanobeads.Molecular imprinted nanobeads with core-shell structure were prepared with Fe3O4@SiO2 as the supporting. The homogeneous polymer films had the thickness of about 22 nm. The as-synthesized surface-imprinted core-shell magnetic beads showed outstanding affinity and selectivity over other structurally related compounds and the resulting composites reusability without obviously deterioration in performance was demonstrated at least five repeated cycles. In addition, the system can be easily separated under an external magnetic field.Molecular imprinted nanobeads with core-shell structure were prepared with magnetic Fe3O4@SiO2-Dye-SiO2 as the supporting. The polymer and FITC layer of Fe3O4@SiO2-MIP had the thickness of about 5.7 nm and 8.7 nm, respectively. The limit of detection is 0.19μmol/L measuraed by photoluminescence spectrometer and the beads can be reused for at least up to 5 times without significant loss of magnetic moment and signal intensity. In addition, the Stem-volmer equations illustrated the mechanism of fluorescent quenching. A molecularly imprinted polymer–graphene oxide (MIP-GO) hybrid material was synthesized with graphene oxide as the support. The average thickness of the polymer grafted on the GO surface is about 3.707 nm. Adsorption experiments demonstrated that the hybrid material has strong affinity, excellent selectivity and reusability. Density functional theory calculations verified that the substrate provides a significantπsurface that could overlap with theπorbitals of 2,4-DCP and obtains stability through electrostatic interaction, resulting in the formation ofπ-πstacking, and the mechanism of the significant improvements on the affinity and selectivity of the MIP-functionalized graphene materials.更多还原