Cannavacciuolo L, Sommer C, Pedersen JS, Schurtenberger P
Institut fur Polymere, Eidgenossische Technische Hochschule, CH-8092 Zurich, Switzerland.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Oct;62(4 Pt B):5409-19. doi: 10.1103/physreve.62.5409.
We present a systematic Monte Carlo study of the scattering function S(q) of semiflexible polyelectrolytes at infinite dilution, in solutions with different concentrations of added salt. In the spirit of a theoretical description of polyelectrolytes in terms of the equivalent parameters, namely, persistence length and excluded volume interactions, we used a modified wormlike chain model, in which the monomers are represented by charged hard spheres placed at distance a. The electrostatic interactions are approximated by a Debye-Huckel potential. We show that the scattering function is quantitatively described by that of uncharged wormlike chains with excluded volume effects provided that an electrostatic contribution is added to the persistence length. In addition we have studied the expansion of the radius of gyration and of the end-to-end distance. The results are in agreement with the picture outlined in the Odijk-Skolnick-Fixman theory, in which the behavior of charged polymers is described only in terms of increasing local rigidity and excluded volume effects. Moreover, the Monte Carlo data are found to be in very good agreement with experimental scattering measurements with equilibrium polyelectrolytes, i.e., giant wormlike micelles formed in mixtures of nonionic and ionic surfactants in dilute aqueous solution, with added salt.
我们对无限稀释下的半柔性聚电解质在不同添加盐浓度溶液中的散射函数S(q)进行了系统的蒙特卡罗研究。本着用等效参数（即持久长度和排除体积相互作用）对聚电解质进行理论描述的精神，我们使用了一种改进的蠕虫状链模型，其中单体由相距a的带电硬球表示。静电相互作用由德拜-休克尔势近似。我们表明，只要在持久长度上加上静电贡献，散射函数就可以由具有排除体积效应的不带电蠕虫状链的散射函数进行定量描述。此外，我们还研究了回转半径和端到端距离的扩展。结果与奥迪克-斯科尔尼克-菲克斯曼理论中概述的情况一致，在该理论中，带电聚合物的行为仅根据局部刚性增加和排除体积效应来描述。此外，发现蒙特卡罗数据与平衡聚电解质的实验散射测量结果非常吻合，即由非离子和离子表面活性剂在稀水溶液中混合并添加盐形成的巨型蠕虫状胶束。
