溶胶凝胶法制备光响应性分子印迹聚合物及其应用研究

【作者】 姜广帅；

【导师】 钟世安；

【作者基本信息】 中南大学 ， 有机化学， 2011， 硕士

【摘要】 分子印迹聚合物是一种新型的三维高度交联的智能材料,已被证实是制备分子识别材料的有效技术。印记就好像一把锁一样只能跟匹配的钥匙兼容,类似于生物系统,如抗体和抗原,酶和底物,激素和受体。分子印迹聚合物的制备是通过交联聚合完成的,模板分子脱去后,形成识别空腔选择性的识别模板分子。通常功能单体含有合适的官能团去匹配模板分子的活性位点,以提高分子印迹聚合物的选择性。本文成功制备了一种新型的光响应性的功能单体,这种功能单体载有硅氧烷可聚合基团和偶氮苯功能基。然后以2,4-二氯苯氧乙酸(2,4-D)和2-甲基-4-氯苯氧乙酸(MCPA)为模板分子成功制备了光响应性的分子印迹聚合物溶胶凝胶材料。发现,将这种新型的功能单体引入到刚性的三维交联的聚合物中,其光异构化性质得以保持。等模板分子从最终的聚合物中洗脱之后,形成了与模板分子在形状、大小和功能相匹配的空穴。主要研究内容如下：1.成功制备了含2,4-D的偶氮苯功能单体和含MCPA的偶氮苯功能单体。这种新型的偶氮苯功能单体一端以共价键结合模板分子,另一端结合3-碘代正丙基三甲氧基硅烷；然后对所制备的功能单体进行了红外表征以及光谱分析。2.利用分子印迹技术,选择不同的功能单体(含2,4-二氯苯氧乙酸的偶氮苯功能单体、含2-甲基-4-氯苯氧乙酸的偶氮苯功能单体)和交联剂(四乙氧基硅烷TEOS),采用溶胶-凝胶法来构建光可控制性的分子印迹有机无机杂化材料,成功制备了两类分子印迹聚合物溶胶凝胶材料。3.对制备的两种分子印迹材料进行了红外表征；为了研究所制备的聚合物材料的表面形态和结构,采用电镜扫描(SEM)对印迹聚合物进行了表征；并对分子印迹材料做了光谱分析,结果证实将光响应性的偶氮苯功能单体嫁接到有机-无机杂化材料中,其光响应性得以保持,制备的分子印迹聚合物对外界刺激具备很好的响应性。4.对制备的2,4-D分子印迹聚合物材料进行了性能和应用探究。吸附结合能力实验表明,分子印迹聚合物材料对模板分子具有较好的结合能力,说明印迹孔穴和孔穴中的活性结合位点导致印迹聚会物对模板分子具有特异识别性。光控制分析物的吸收和释放实验表明,受体位点的构造和印迹的亲和性是受光控制的并且可逆的,经过三次辐照周期没有失去特异性和可逆性。通过检测样品中目标分析物浓度与刺激响应材料光异构化速率常数的关系,得到了目标分析物的标准曲线。5.采用分子模拟的方式从理论上证实制备MCPA分子印迹聚合物材料的可行性,对制备的MCPA分子印迹聚合物材料进行了性能和应用探究,如吸附结合能力、分子特异性识别能力、是否具有光控制分析物的吸收和释放,并通过检测样品中目标分析物浓度与刺激响应材料光异构化速率常数的关系,得到了其标准曲线,开辟分子印迹杂化材料在化学传感和环境分析中的新应用。更多还原

【Abstract】 Molecularly imprinted polymers (MIP) are a new type of three-dimensional, highly cross-linked smart materials, which have been demonstrated to be a useful technique for the preparation of molecular recognition materials. The imprint is like a lock that is only compatible with the correct key, similar to biological systems, such as antibodies and antigens, enzymes and substrates, and hormones and receptors. A crosslink polymerization is performed to fix the desired complex. After the template molecules are removed, binding cavities that recognize the applicable template are left to rebind selected molecules. Generally, a functional monomer has an appreciative group to match the active site of the template molecule, which makes the complex stable and improve the selectivity of the MIPs.In this study, a novel photoresponsive functional monomer, bearing a siloxane polymerisable group and azobenzene moieties was synthesized, and then a photoresponsive molecularly imprinted sol-gel polymers are successfully fabricated from the synthesized functional monomer, using 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxy acetic acid (MCPA) as a molecular template. The photoisomerization properties of the functional monomer are retained after incorporation into the rigid 3D crosslinked polymer matrix. The template is then removed from the resulting polymer to generate pores, which are complementary to the template in shape, size and functionality.The main component of the experimental study as follows:1. Frist, a novel photoresponsive functional monomer, containing molecule template 2,4-D and MCPA was synthesized using organic synthesis. This new type of azobenzene functional monomer covalently bound at one end to the template molecule and the other end with 3-Iodopropyltrimethoxysilane; then the functional monomer we prepared was characterized by infrared spectroscopy.2. In this study, a route to two types of photoresponsive molecularly imprinted sol-gel materials was presented, which have a photoswitchable and selective affinity with molecule template accordingly. The photoresponsive molecularly imprinted polymers were structured from different functional monomers (azobenzene functional monomer including 2,4-D, or MCPA) and crosslinker (tetraethoxysilane) using molecular imprinting technique by a sol-gel route.3. Two kinds of molecularly imprinted materials we prepared were characterized by IR; scanning electron microscopy (SEM) was characterized for research of the surface morphology and structure of polymer materials prepared; spectral analysis was made to the materials, the results confirm that after photoresponsive azobenzene functional monomer grafted to the organic-inorganic hybrid materials, the photoisomerization properties were maintained, and the molecularly imprinted polymers we prepared possess good response to external stimulation.4. Application and performance were explored on 2,4-D imprinted polymer materials prepared. Binding experiments showed that the imprinted polymer materials have a good binding capacity with the template 2,4-D, indicating that imprinting cavities and the active binding site in the cavities lead the MIP to the specific recognition of template molecules. Investigation of photoregulated release and uptake shows that the near-quantitative uptake of the template molecule after isomerization of the azobenzene chromophores in the MIP receptor sites over three irradiation cycles demonstrated that the binding sites exhibited good reversibility, without loss of specificity. The relationship between the concentration of the 2,4-D and the trans-to-cis photoisomerization rate constant was investigated, the standard curve was made, and the curve was feasible theoretically analyzed.5. Computational simulation theoretically confirms that the design of the molecularly imprinted polymer (MIP) was feasible. Application and performance were explored on MCPA molecularly imprinted polymer materials prepared, such as adsorption binding capacity, ability of specific molecular recognition, and investigation of photoregulated release and uptake of target analyte. In addition, the relation between the concentration of the MCPA and the trans-to-cis photoisomerization rate constant was investigated, and we have successfully shown that the concentration of the MCPA can be quantitatively determined through the trans-to-cis photoisomerization rate of the azobenzene chromophore. The standard curve was made, opening up new applications in chemical sensing and environmental analysis about molecularly imprinted polymer.更多还原