Synthesis and Aqueous Solution Behavior of a pH-Responsive Schizophrenic Diblock Copolymer
Synthesis and Aqueous Solution Behavior of a pH-Responsive Schizophrenic Diblock Copolymer
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DOI：
10.1021/la020951l
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发表时间：
2003-04
期刊：
影响因子：
3.9
通讯作者：
Shiyong Liu and;S. Armes
中科院分区：
文献类型：
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作者：
Shiyong Liu and;S. Armes
采用原子转移自由基聚合法合成了一种新型的两性离子聚[4-乙烯基苯甲酸-嵌段-2-甲基丙烯酸N-（吗啉代）乙酯]（VBA 63-b-MEMA 123）二嵌段共聚物。该酸性嵌段的pKa为7.1，高于MEMA嵌段的共轭酸的pKa（pKa = 4.9）。这对该两性离子二嵌段共聚物的水溶液性质具有重要影响。例如，与其他两性离子二嵌段共聚物如聚[甲基丙烯酸-嵌段-2-（二甲基氨基）乙基甲基丙烯酸酯]不同，在pH 6.2左右的等电点（IEP）下不发生沉淀。这很可能是由于在此pH值下，EMA和MEMA嵌段上的电荷密度相对较低。VBA 63 − MEMA 123共聚物表现出有趣的“精神分裂”胶束化行为。低于pH 6时，形成VBA-核胶束，而高于pH 6时，二嵌段共聚物可以溶解为单聚体。在足够的...
A novel zwitterionic poly[4-vinylbenzoic acid-block-2-N-(morpholino)ethyl methacrylate] (VBA63-b-MEMA123) diblock copolymer was synthesized via atom transfer radical polymerization using protecting group chemistry for the acidic residues. The acidic VBA block has a pKa of 7.1, which is higher than that of the conjugate acid of the MEMA block (pKa = 4.9). This has important consequences for the aqueous solution properties of this zwitterionic diblock copolymer. For example, unlike other zwitterionic diblock copolymers such as poly[methacrylic acid-block-2-(dimethylamino)ethyl methacrylate], precipitation does not occur at the isoelectric point (IEP) of around pH 6.2. This is most likely due to the relatively low degree of charge density on both the VBA and MEMA blocks at this pH. The VBA63−MEMA123 copolymer exhibits interesting “schizophrenic” micellization behavior. Below pH 6, VBA-core micelles are formed, while above pH 6, the diblock copolymer can be dissolved as unimers. In the presence of sufficient ...