Association behavior of ampholytic diblock copolymers
Association behavior of ampholytic diblock copolymers
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DOI：
10.1021/ma9907441
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发表时间：
1999-12-14
期刊：
影响因子：
5.5
通讯作者：
Stuart, MAC
中科院分区：
文献类型：
--
作者：
Goloub, T;de Keizer, A;Stuart, MAC
研究了二嵌段共聚物与带相反电荷的水溶性聚(二甲基氨基)乙基甲基丙烯酸酯(AMA)和聚甲基丙烯酸钠(SPM)嵌段在水溶液中的缔合，作为pH值和两个嵌段的链段比的函数。这些共聚物聚集体的尺寸和结构通过动态光散射、电动和电位测量来表征。缔合过程主要是静电驱动的。在等电点附近的 pH 值下，会发生无限的聚集或相分离。该区域的位置取决于两个块的段比。如果 pH 值远离等电点，则共聚物分子的净电荷会导致带电分子组装体。当 pH 值高于 10 或低于 4 时，即其中一个嵌段完全不带电，共聚物组装体仍然存在。还研究了相应的带相反电荷的均聚电解质混合物的溶液行为。尽管均聚物分子的长度较长，但带电均聚物复合物的尺寸小于共聚物。
The association of diblock copolymers with oppositely charged, water-soluble poly(dimethylamino)ethyl methacrylate (AMA) and sodium polymethacrylate (SPM) blocks was studied in aqueous solution as a function of pH and the segment ratio of the two blocks. The size and the structure of these copolymer aggregates were characterized by dynamic light scattering, electrokinetic, and potentiometric measurements. The association process is mainly electrostatically driven. At pH values around the isoelectric point, unlimited aggregation or phase separation takes place. The position of this region depends on the segment ratio of the two blocks. If the pH is moved away from the isoelectric point, the net charge of the copolymer molecules leads to charged molecular assemblies. At pH values higher than 10 or lower than 4, i.e., one of the blocks is entirely uncharged, copolymer assemblies still exist. The solution behavior of the corresponding oppositely charged homopolyelectrolyte mixtures was also studied. The size of the charged homopolymer complexes is smaller than that for copolymers although the length of the homopolymer molecules is higher.