化学学报 ›› 2011, Vol. 69 ›› Issue (23): 2773-2780.DOI: 10.6023/A1105112 上一篇    下一篇

研究论文

聚电解质混合物在均匀带电平面上吸附的密度泛函研究

王蕾*, 梁好均   

  1. (中国科学技术大学化学与材料科学学院 合肥 230026)
  • 收稿日期:2011-05-11 修回日期:2011-07-10 出版日期:2011-12-14 发布日期:2011-08-15
  • 通讯作者: 王蕾 E-mail:wanglei@mail.ustc.edu.cn
  • 基金资助:

    国家自然科学基金

Density Functional Theory for Polyelectrolyte Mixtures Adsorption on Uniformly Charged Planar Surface

WANG Lei, LIANG Hao-Jun   

  1. (School of Chemistry and Material Science, University of Science and Technology of China, Hefei 230026)
  • Received:2011-05-11 Revised:2011-07-10 Online:2011-12-14 Published:2011-08-15
  • Contact: Lei WANG E-mail:wanglei@mail.ustc.edu.cn

采用非局域密度泛函理论计算方法(NLDFT), 我们研究了两种带相反电荷的聚电解质混合物在均匀带电平面上的吸附以及吸附层的电荷反转现象. 我们对表面带电密度和聚电解质链段的价态对吸附的影响做了系统研究, 发现在体系中不含小离子的情况下, 当体系中两种聚电解质链段都为单价时, 和表面带相反电荷的聚电解质链能够吸附在平面上, 而和表面带相同电荷的聚电解质链和表面之间相互排斥, 整个过程就是表面电荷被与之带相反电荷的聚电解质链上所带电荷中和的过程, 没有出现明显的电荷反转现象|当体系中作为反离子存在的聚电解质链段价态为二价时, 和表面带相同电荷的聚电解质链能在表面上吸附, 出现明显的电荷反转现象. 理论研究表明, 以反离子居中为媒介的静电相关效应是聚电解质混合物出现多层吸附的主要驱动力之一.

关键词: 密度泛函理论(DFT), 聚电解质, 多层吸附, 反离子价态, 静电相关效应

A non-local density functional theory (NLDFT) is used to investigate a mixture of two species of polyelectrolytes which are oppositely charged near a uniformly charged planar surface. In the absence of small ions, we present a systematic study on the effects of surface charge density and the valence of the polyion segments, and the results reveal that little charge inversion occurs except when the polyions existing as counterions bear two charges per segment. With monovalent segments of all polyions, only oppositely-charged polyions can be adsorbed on the surface, it is a neutralization process of the surface charges by the charges born by the adsorbed polyions. The theoretical investigation indicates that the electrostatic correlation mediated by counterions is one of the major underlying forces responsible for the alternating adsorption of oppositely charged polyions.

Key words: density functional theory (DFT), polyelectrolyte, layer-by-layer adsorption, counterion valence, electrostatic correlation

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