Reverse Response of an Ion-Recognition Polyampholyte to Specific Ion Signals at Different pHs
Reverse Response of an Ion-Recognition Polyampholyte to Specific Ion Signals at Different pHs
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DOI：
10.1021/ma801936t
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发表时间：
2009-01
期刊：
影响因子：
5.5
通讯作者：
Nobuo Hara;H. Ohashi;Taichi Ito;Takeo Yamaguchi
中科院分区：
文献类型：
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作者：
Nobuo Hara;H. Ohashi;Taichi Ito;Takeo Yamaguchi
首次合成并表征了[3-（甲基丙烯酰氨基）丙基]三甲基氯化铵（MAPTAC）、丙烯酸（AA）和苯并[18]冠-6-丙烯酰胺（BCAm）的两性离子识别线性共聚物。在该共聚物中，MAPTAC单元具有正电荷。AA单元具有取决于pH的负电荷。BCAm单元的冠受体与特定离子（例如Ba 2+）形成络合物，因为高络合物形成常数表现为固定的正电荷。因此，这些共聚物表现为离子识别聚两性电解质，并在等于等电点（IEP）的pH值下收缩，当BCAm与阳离子络合时，其转变为更高的pH值。此时，BCAm也随着伴随阳离子的水合水而变得亲水。由于这两种效应的结合，我们发现，在不同的pH值下，响应于相同的离子信号，溶胀和收缩的相反行为发生。
We synthesized and characterized for the first time an ampholytic ion-recognition linear copolymer of [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC), acrylic acid (AA), and benzo[18]crown-6-acrylamide (BCAm). In this copolymer, the MAPTAC unit has a positive charge. The AA unit has a negative charge that depends on the pH. The crown receptor of the BCAm unit forms a complex with specific ions such as Ba2+ because of the high complex formation constant which behaved like a fixed positive charge. Thus, the copolymers behaved as an ion-recognition polyampholytes and shrank at a pH equal to the isoelectric point (IEP), which shifted to a higher pH when the BCAm complexed with a cation. At that time, the BCAm also became hydrophilic with water of hydration accompanied by the cation. As a result of the combination of these two effects, we found that the reverse behaviors of swelling and shrinking occurred at different pHs in response to the same ion signal.