Diffusion motions and microphase separation of styrene-butadiene diblock copolymer in solution. 2. Behavior in n-decane in the dilute solution region
Diffusion motions and microphase separation of styrene-butadiene diblock copolymer in solution. 2. Behavior in n-decane in the dilute solution region
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苯乙烯-丁二烯二嵌段共聚物在溶液中的扩散运动和微相分离。
DOI：
10.1021/ma00213a024
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发表时间：
1990
期刊：
影响因子：
5.5
通讯作者：
Y. Tsunashima
中科院分区：
文献类型：
--
作者：
Y. Tsunashima
本文报道了苯乙烯-丁二烯（SB）二嵌段共聚物（A_f_w = 9.73 × 104，苯乙烯含量为29.3wt%）在正癸烷（B亚链的选择性溶剂）中的稀溶液性质。在1 × 10 ~（-6）~ 7.24 × 10~（-3）g·cm ~（-3）范围内，扩散系数随聚合物浓度的变化呈现两级跃变。SB二嵌段共聚物仅在c< 3.8 X 10 - 6 g cm-3的极稀浓度下能够分子分散，而在c> 1.1 X 10- 4g cm-3的相对稀浓度下，共聚物形成近单分散胶束。胶束是100片SB共聚物的分子间缔合，并且由被溶胀的B亚链包围的S亚链的硬核构成。用“两相”同心球模型对胶束的尺寸进行了分析，结果表明，胶束的核半径为10.2 nm，壳层厚度为33.3 nm，胶束整体的表观回转半径为33.8 nm，B亚链在壳层中处于高度伸展状态。此外，胶束还表现出内部运动，这可能主要是由于胶束颗粒中B亚链相对于S亚链的相对质心运动，即特别是由于壳层中发生的浓度波动。这种浓度波动可能是由于B亚链的高链柔性在壳层中高度溶胀所致。
The dilute solution propertiesobserved by dynamic light scattering spectroscopy at 25 C are reported for a styrene-butadiene (SB) diblock copolymer (Afw= 9.73 X 104, a styrene content of 29.3 wt%) in n-decane, a selective solvent to the B subchain. A double-step transition of the diffusion coeffi-cient is assured as a function of the polymer concentrationin therange from 1 X 10™ 6 to 7.24 X 10~ 3 g cm-3. The SB diblock copolymer is able to disperse molecularly only at an extremely dilute concentration of c< 3.8 X 10™ 6 g cm-3, while at a relatively dilute concentration of c> 1.1 X 10-4 g cm-3 the copolymer forms near-monodisperse micelles. The micelles are an intermolecular association of 100 pieces of SB copolymers and are constructed from a hard core of S subchains surrounded by swollen B subchains. The micellar size analyzed with a “two-phase” concentric sphere model indicates that the core radius is 10.2 nm, the shell thickness is 33.3 nm, and the apparent radius of gyration of the micelle as a whole is 33.8 nm; the B subchains are in a highly extendedstate in the shell. Moreover, the micelle shows internal motions which might be mainly due to the relative center-of-mass motion of the B subchains with respect to the S sub-chains in the micellar particle, ie, due especially to the concentrationfluctuation taking place in theshell. The concentration fluctuation may be caused by high chain flexibility of B subchainswhich swell highly in the shell.