Recognition of Alkyl Groups on a Polymer Chain by Cyclodextrins
Recognition of Alkyl Groups on a Polymer Chain by Cyclodextrins
复制标题
环糊精对聚合物链上烷基的识别
DOI：
10.1021/ma970269b
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发表时间：
1997
期刊：
影响因子：
5.5
通讯作者：
M. Kamachi
中科院分区：
文献类型：
--
作者：
A. Harada;H. Adachi;Y. Kawaguchi;M. Kamachi
自世纪前环糊精被发现以来，大量低分子量化合物的包合物被制备和表征。[1]只是在最近几年才发现环糊精不仅能与小分子形成包合物，而且还能与聚合物形成包合物。[2]我们以前曾报道过R-CD与聚乙二醇（PEG）、3 β-CD与聚丙二醇（PPG）、4和γ-CD与聚甲基乙烯基醚（PMVE）5和聚异丁烯形成复合物。6发现这些复合物形成通道型包合物：主链包含在CD形成的通道中。7大分子通过识别其主链和侧链基团而被其他分子识别。在生物系统中，侧链的识别在构建超分子结构、实现功能和维持生命方面起着重要作用。8例如，抗体通过识别其侧链来识别抗原。9 DNA通过侧链的顺序相互识别。因此，我们研究了连接在聚合物链上的客体部分与CD的相互作用。我们发现，CD有效地和选择性地结合聚合物链上的客体部分。通过丙烯酰胺与正丁醇、异丁醇、叔丁醇、正己醇、异辛醇和十二烷醇的甲基丙烯酸酯或丙烯酸酯的共聚，已经制备了在主链上具有客体的聚合物。我们选择丙烯酰胺作为共聚单体，因为均聚物可溶于水，所以共聚物的溶解度可以通过共聚单体比率来控制。甲基丙烯酸酯和丙烯酸酯被选择为在单体单元中具有客体的其他共聚单体，因为它们可以通过加成聚合（例如自由基聚合和离子聚合）容易地与丙烯酰胺聚合。当R-CD加入到丙烯酰胺和甲基丙烯酸正丁酯（丙烯酰胺单元：甲基丙烯酸正丁酯单元为5：1）的不溶性共聚物的悬浮液中时，不溶性聚合物溶解于水中，得到均匀的溶液。相比之下，当β-CD加入到甲基丙烯酸正丁酯的相同不溶性共聚物的悬浮液中时，没有变化。这些结果表明，R-CD包括不溶性聚合物的正丁基部分以产生可溶性复合物，但β-CD不包括聚合物的正丁基部分。相反，当β-CD加入到丙烯酰胺和甲基丙烯酸叔丁酯（丙烯酰胺单元：甲基丙烯酸叔丁酯单元为5：1）的不溶性共聚物的悬浮液中时，不溶性聚合物被增溶
Since cyclodextrins (CDs) were discovered a century ago, a large number of inclusion complexes with low molecular weight compounds have been prepared and characterized. 1 It is only in recent years that cyclodextrins were found to form inclusion complexes not only with small molecules but also with polymers. 2 Previously, we reported that R-CD forms complexes with poly-(ethylene glycol)(PEG), 3 β-CD with poly (propylene glycol)(PPG), 4 and γ-CD with poly (methyl vinyl ether)(PMVE) 5 and polyisobutylene. 6 These complexes were found to form channel type inclusion complexes: a main chain is included in the channel formed by CDs. 7 Macromolecules are identified by other molecules through the recognition of their main chains and side chain groups. In biological systems, recognition of side chains plays an important role in constructing supramolecular structures, achieving functions, and maintaining their lives. 8 For example, antigens are identified by antibodies through recognition of their side chains. 9 DNAs recognize each other through the sequence of the side chains. Accordingly, we studied the interactions of guest moieties attached on a polymer chain with CDs. We found that CDs bind guest moieties on a polymer chain efficiently and selectively. Polymers having guests on a main chain have been prepared by copolymerization of acrylamide with methacrylates or acrylates of n-butanol, isobutyl alcohol, tert-butyl alcohol, n-hexanol, isooctanol, and dodecanol. We chose acrylamide as a comonomer because the homopolymer is soluble in water so the solubilities of the copolymer can be controlled by the comonomer ratios. Methacrylates and acrylates were chosen other comonomers having guests in a monomeric unit because they can be readily polymerized with acrylamide by addition polymerization (such as radical polymerization and ionic polymerization). We have obtained both water-soluble polymers and water-insoluble polymers depending on the comonomer ratios.When R-CD was added to the suspension of insoluble copolymers of acrylamide and n-butyl methacrylate (acrylamide unit: n-butyl methacrylate unit) 5: 1), the insoluble polymer was solubilized into water to give a homogeneous solution. In contrast, when β-CD was added to the suspension of the same insoluble copolymer of n-butyl methacrylate, there was no change. These results indicate that R-CD includes an n-butyl moiety of the insoluble polymer to give a soluble complex, but β-CD did not include an n-butyl moiety of the polymer. On the contrary, when β-CD was added to the suspension of the insoluble copolymer of acrylamide and tert-butyl methacrylate (acrylamide unit: tert-butyl methacrylate unit) 5: 1), the insoluble polymer was solubilized