Controlling micellar structure of amphiphilic charged triblock copolymers in dilute solution via coassembly with organic counterions of different spacer lengths
Controlling micellar structure of amphiphilic charged triblock copolymers in dilute solution via coassembly with organic counterions of different spacer lengths
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DOI：
10.1021/ma0609026
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发表时间：
2006-09-19
期刊：
影响因子：
5.5
通讯作者：
Pochan, Darrin J.
中科院分区：
文献类型：
--
作者：
Cui, Honggang;Chen, Zhiyun;Pochan, Darrin J.
通过与不同的二胺共组装，在混合四氢呋喃（THF）/水溶液中组装聚（丙烯酸）-嵌段-聚（丙烯酸甲酯）-嵌段聚苯乙烯（PAA-b-PMA-b-PS）三嵌段共聚物的胶束结构，包括圆盘、环形、圆柱体和球体。在恒定的溶液组成（THF：H2O、聚合物浓度和二胺浓度）下，组装结构的界面曲率主要由二胺链结构决定。研究发现，二胺的两个胺端基与不同 PAA 冠嵌段的酸基相互作用产生的链间结合决定了最终的组装结构。随着间隔基长度的增加，具有亲水间隔基的二胺诱导形成具有较大界面曲率的胶束。随着亲水间隔基长度的逐渐增加，观察到盘状胶束、圆柱形胶束或球形胶束。当间隔基长度小于六个亚甲基单元时，具有可变疏水间隔基的二胺显示出类似的效果。较长疏水二胺的应用对界面曲率具有相反的影响。这种效应归因于疏水性二胺烃连接链与 PMA-b-PS 疏水性核心的相互作用。这些发现表明了一种用多价有机抗衡离子调节胶束结构的简单方法。通过透射电子显微镜表征组装形态，并通过溶液态核磁共振波谱研究二胺与PAA嵌段的酸性单元的相互作用。
Micelle structures from the assembly of poly( acrylic acid)- block- poly( methyl acrylate)- blockpolystyrene ( PAA- b- PMA- b- PS) triblock copolymers in mixed tetrahydrofuran ( THF)/ water solution, including disks, toroids, cylinders, and spheres, were targeted by coassembling with different diamines. At constant solution composition ( THF: H2O, polymer concentration, and diamine concentration), the interfacial curvature of the assembled structures was determined primarily by diamine chain structure. It was found that interchain binding from the interaction of the two amine end groups of diamines with acid groups from different PAA corona blocks governs the final assembled structures. Diamines with hydrophilic spacers induced the formation of micelles with larger interfacial curvature as the spacer length increased. Disklike micelles, cylindrical micelles, or spherical micelles were observed with the gradual increase of hydrophilic spacer length. Diamines with variable hydrophobic spacers showed a similar effect when the spacer length was less than six methylene units. Application of longer hydrophobic diamines had a reverse effect on the interfacial curvature. This effect was attributed to the interaction of hydrophobic diamine hydrocarbon linking chains with the PMA- b- PS hydrophobic core. These findings indicate an easy method to tune micelle structure with multivalent organic counterions. Assembled morphologies were characterized by means of transmission electron microscopy, and the interaction of diamines with acidic units of the PAA block segments was studied by solution- state nuclear magnetic resonance spectroscopy.