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arXiv 0901.1613cond-mat.softcond-mat.stat-mech
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嵌段共聚物/均聚物共混体系中胶束的形成:自洽场论与实验及标度理论的比较

Micelle formation in block copolymer/homopolymer blends: comparison of self-consistent field theory with experiment and scaling theory

M. J. Greenall, D. M. A. Buzza, T. C. B. McLeish

摘要:

采用自洽场论(SCFT)方法研究了聚苯乙烯-丁二烯嵌段共聚物与均聚苯乙烯共混体系中球形胶束的形成。胶束的核心半径,冠层厚度和临界胶束浓度作为聚合物的分子量和组成的二嵌段的函数计算。我们的结果进行了比较与早期的标度理论和X射线散射数据。自洽场论和实验对胶束结构的一致性有时是定量的,通常比标度理论更成功。对于具有相对轻的核心嵌段的共聚物,SCFT预测的临界胶束浓度提高了一个数量级的缩放理论。在较重的核心块的情况下,SCFT预测的临界胶束浓度不太好,由于不准确的建模的散装化学势。总体而言,我们发现,SCFT给出了一个非常好的描述球形胶束的形成,因此表明,平均场,平衡的方法是有效的,这些系统。

英文摘要:

We present a self-consistent field theory (SCFT) study of spherical micelle formation in a blend of poly(styrene-butadiene) diblocks and homopolystyrene. The micelle core radii, corona thicknesses and critical micelle concentrations are calculated as functions of the polymer molecular weights and the composition of the diblocks. Our results are compared with an earlier scaling theory and with X-ray scattering data. The agreement between self-consistent field theory and experiment for the micelle structure is sometimes quantitative and is generally more successful than scaling theory. For copolymers with relatively light core blocks, SCFT predictions for the critical micelle concentration improve over those of scaling theories by an order of magnitude. In the case of heavier core blocks, SCFT predicts the critical micelle concentration less well due to inaccuracies in the modelling of the bulk chemical potential. Overall, we find that SCFT gives a very good description of spherical micelle formation and hence demonstrate that a mean-field, equilibrium approach is valid for these systems.

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