Micellization of strongly segregated block copolymers
Micellization of strongly segregated block copolymers
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DOI：
10.1063/1.471723
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发表时间：
1996-06-22
影响因子：
4.4
通讯作者：
Antonietti, M
中科院分区：
文献类型：
--
作者：
Forster, S;Zisenis, M;Antonietti, M
采用阴离子聚合法合成了一系列苯乙烯-b-4-乙烯基吡啶（PS-P4 VP）型嵌段共聚物。在甲苯中，PS嵌段的选择性溶剂，形成具有窄分子量分布的良好定义的胶束。胶束的大小和形状的特征在于静态（SLS）和动态光散射（DLS），和电子显微镜（EM）。聚集数Z表现出与（NP 4VPNPS-0.79）-N-1.93成比例的缩放关系7，其中N是每个嵌段的聚合度。我们发现这种行为接近Z类似于（NANB-0.8）-N-2限制标度律，这似乎是一个特点，强烈隔离的二嵌段和三嵌段共聚物系统，以及低分子量的阳离子，阴离子和非离子表面活性剂。一个简单的胶束化模型预测聚集，表面活性剂，二嵌段，三嵌段和接枝共聚物的数量。通过DLS测量的电晕尺寸D-h标度为D-h与Z（0.21）N（PS）（0.63）成正比，与理论预测D一致，类似于良溶剂中星形分子的Z（1/5）N（B）（3/5）。既没有观察到单体，也没有观察到临界胶束浓度。相反，在非常低的浓度下，由于形成大颗粒，过量散射强度增加。(C)1996年美国物理学会。
Series of diblock copolymers of the type poly(styrene-b-4-vinylpyridine) (PS-P4VP) are synthesized via anionic polymerization. In toluene, a selective solvent for the PS block, well-defined micelles with narrow molecular weight distribution are formed. Size and shape of the micelles are characterized by static (SLS) and dynamic light scattering (DLS), and electron microscopy (EM). The aggregation number Z exhibits a scaling relation 7 proportional to (NP4VPNPS-0.79)-N-1.93, where N is the degree of polymerization of each block. We find this behavior close to a Z similar to (NANB-0.8)-N-2 limiting scaling law which appears to be a characteristic of strongly segregated diblock and triblock copolymer systems as well as low molecular weight cationic, anionic, and nonionic surfactants. A simple micellization model is developed that predicts aggregation;numbers of surfactants, diblock, triblock, and graft copolymers. The corona dimension D-h as measured by DLS scales as D-h proportional to Z(0.21)N(PS)(0.63) in agreement with the theoretical prediction D similar to Z(1/5)N(B)(3/5) for starlike molecules in good solvents. Neither unimers nor a critical micelle concentration are observed. Instead at very low concentrations the excess scattering intensity increases due to the formation of large particles. (C) 1996 American Institute of Physics.