Visualizing worm micelle dynamics and phase transitions of a charged diblock copolymer in water
Visualizing worm micelle dynamics and phase transitions of a charged diblock copolymer in water
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DOI：
10.1021/jp0459559
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发表时间：
2005-03-10
影响因子：
3.3
通讯作者：
Discher, DE
中科院分区：
文献类型：
--
作者：
Geng, Y;Ahmed, F;Discher, DE
嵌段共聚物两亲物的组装体有时被视为玻璃状的、冻结的或静态的胶体，特别是在强烈分离的溶液中。在这里，我们可视化荧光显微镜和原子力显微镜的动态和过渡的单一圆柱形胶束和囊泡组成的带电的二嵌段共聚物在水中。在映射的盐和pH值依赖的相位diagranis的近对称的聚（丙烯酸）-聚丁二烯，低pH值和高盐（NaCl，氯化钙）中和和屏幕的带电电晕足以促进膜的形成和-enerate囊泡。盐和中性pH值的降低增加了冠内排斥，并驱动向多分支圆柱体和高度稳定但流动和灵活的蠕虫胶束的转变。Ca 2+使圆柱体变硬，并使它们相对于球体稳定。进一步增加冠内排斥产生球形胶束的碎片和夹断在蠕虫的两端。过渡动力学和相图都表明，二价阳离子在稳定所有非球形形态方面比一价阳离子有效约5 - 10倍。
Assemblies of block copolymer amphiphiles are sometimes viewed as glassy, frozen, or static colloids, especially in strongly segregating solutions. Here, we visualize by fluorescence microscopy and AFM the dynamics and transitions of single cylindrical micelles and vesicles composed of a charged diblock copolymer in water. In mapping the salt- and pH-dependent phase diagranis of a near-symmetric diblock of poly(acrylic acid)-polybutadiene, low pH and high salt (NaCL, CaCl2) neutralize and screen the charged corona sufficiently to foster membrane formation and -enerate vesicles. Decreased salt and neutral pH increases intra-coronal repulsion and drives a transition to multi-branched cylinders and highly stable, but fluid and flexible, worm micelles. Ca2+ both stiffens cylinders and stabilizes them relative to spheres. Further increase of intra-coronal repulsion generates spherical micelles by fragmentation and pinch-off at the ends of worms. Both the transition kinetics and phase diagrams indicate divalent cation is about 5 - 10-fold more effective than monovalent in stabilizin- all nonspherical morphologies.