【作者】 殷民喜；

【导师】 王力彦；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2012， 硕士

【摘要】 用主客体包合是调控热敏高分子的浊点的一种简便的方法。例如尺寸合适的环糊精（CD）与热敏高分子侧基发生包合，通过改变热敏高分子侧基的亲疏水性调控热敏高分子溶液的浊点。环糊精与聚合物侧基的包合是一个快速交换的平衡，环糊精浓度越高，环糊精与聚合物侧基形成的包合复合物浓度越高，溶液浊点升高的越多。由环糊精和偶氮苯化合物组成的光控超分子体系是超分子化学领域的活跃的研究方向。偶氮苯吡啶盐Azo-Py~+是一种水溶性的偶氮苯衍生物，在紫外光/可见光交替照射下，它的构型能发生反式/顺式可逆的转变。Azo-Py~+为反式构型时，可以与α-CD形成超分子复合物，而顺式的Azo-Py~+几乎不能与α-CD作用。在本论文中，我们以热敏高分子聚（3-乙氧基丙基）丙烯酰胺（PEPAm）为研究对象。根据我们的研究经验，α-CD可能与PEPAm侧基包合形成超分子复合物，使高分子溶液浊点升高。我们把PEPAm/α-CD超分子体系和Azo-Py~+/α-CD超分子体系结合起来。在PEPAm/α-CD/Azo-Py~+混合溶液中，通过光控的α-CD和偶氮苯基团的包合/解离可以调节溶液中自由环糊精的浓度，这会导致PEPAm溶液浊点发生可逆变化。在第二章中，我们通过自由基聚合的方法合成了PEPAm，测试了不同尺寸的环糊精对PEPAm溶液浊点的影响：在相同摩尔浓度时，α-CD使高分子溶液浊点显著升高，而β-CD和γ-CD对溶液浊点几乎没有影响。NOESY核磁实验结果表明PEPAm侧基和α-CD发生了包合作用。我们用Job’s method确定α-CD和PEPAm侧基包合的化学计量比为1，并用核磁滴定得方法测定包合常数为6.5±1.1L/mol。我们还研究了不同浓度α-CD对PEPAm溶液浊点的影响，发现PEPAm溶液浊点随α-CD浓度的增大而升高，并且浊点与α-CD浓度之间的关系可以用基于化学平衡推导出的方程来描述。在第三章中，我们在PEPAm/α-CD溶液中加入竞争性的客体Azo-Py~+。由于反式Azo-Py~+与α-CD的结合常数比其与PEPAm侧基的结合常数大很多，溶液中大部分的α-CD与Azo-Py~+结合，溶液中自由的α-CD浓度很低，导致溶液的浊点降低。PEPAm/α-CD/Azo-Py~+合溶液经紫外光照射后，Azo-Py~+构型由反式转变为顺式，顺式构型的Azo-Py~+与α-CD的结合常数很低，Azo-Py~+/α-CD复合物的解离使自由的α-CD浓度增大，导致PEPAm溶液的浊点升高。用可见光照射混合溶液，Azo-Py~+由顺式转变为反式，自由的α-CD浓度减小，导致溶液浊点降低。我们把PEPAm/α-CD/Azo-Py~+混合溶液恒定在38°C，成功实现了PEPAm/α-CD/Azo-Py~+混合溶液透过率的光控可逆变化，并且至少维持五个周期。更多还原

【Abstract】 Host-guest inclusion complexation is a simple method of tuning cloud point ofthermosensitive polymers. For example, cyclodextrins (CD) with suitable size caninclude the side group of thermosensitive polymer and therefore change thehydrophilicity of the side group, which causes the increase of the cloud point ofpolymer solution. The inclusion complexation of side group of polymer withcyclodextrin is a fast exchange equilibrium. In the thermosensitive polymer solution,the higher the concentration of CD is, the more inclusion complex is formed, whichcauses a larger increase of the cloud point.Photocontrolled supramolecular system based on CD and azo compounds is a hotresearch topic in supramolecular chemistry field.4-(Phenylazo)benzylpyridiniumbromide (Azo-Py~+) is a water-soluble derivative of azobenzene, trans and cis formsof which can be reversibly interconverted upon light irradiation. Trans-Azo-Py~+canbe well-recognized by α-CD. However, when trans-Azo-Py~+is transformed tocis-Azo-Py~+, α-CD cannot include the cis isomer any more because of the mismatchbetween the host and guest.In this work, poly(ethoxypropylacrylamide)(PEPAm) was studied. According toour experience, α-CD could form supramolecular complex with side chain of PEPAm,which probably causes the increase of the cloud point of PEPAm solution. The twosupramolecular systems of PEPAm/α-CD and Azo-Py~+/α-CD were combined. InPEPAm/α-CD/Azo-Py~+solution, photocontrolled inclusion and exclusion of Azo-Py~+with α-CD can be used to change the concentration of free α-CD, which can causereversible changes of the cloud point of PEPAm solution.In the second chapter, we synthesized PEPAm by radical polymerization, andinvestigated effects of different sizes of CD on cloud point of PEPAm solution. α-CDshowed a significant effect on cloud point of PEPAm whereas β-CD and γ-CD hadalmost no effect. The inclusion complexation between α-CD and the side group of PEPAm was confirmed by the NOESY NMR spectrum. The inclusion stoichiometryof α-CD and PEPAm equals1, which was determined with Job’s method. Anassociation constant of6.5±1.1L/mol was obtained by NMR titration. Finally, thecloud point of PEPAm increased with an increase in the molar concentration of α-CD.The relationship between cloud point and the concentration of α-CD can be describedwith an equation based on inclusion complexation equilibrium.In the third chapter, Azo-Py~+is added to PEPAm/α-CD solution. Most of α-CDformed inclusion complexes with Azo-Py~+, because the association constant ofAzo-Py~+and α-CD is much larger than that of PEPAm and α-CD. The cloud point ofthe solution decreased owing to the decrease in the concentration of free α-CD. Astrans-Azo-Py~+was isomerized to cis-Azo-Py~+upon irradiation with UV light, theconcentration of free α-CD was increased because the association constant ofcis-Azo-Py~+and α-CD is less than that of trans-Azo-Py~+and α-CD. Consequently, thecloud point of PEPAm solution was increased. Succeeding irradiation with visiblelight led to reverse conversion of Azo-Py~+configuration. The cloud point wasdecreased owing to the decrease in the concentration of free α-CD. Furthermore, thetransmittance of the solution can be changed reversibly for at least5cycles withalternate irradiations of UV and visible light at38°C.更多还原