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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.
Using nonlocal density functional theory (NLDFT), we studied the adsorption of the two oppositely charged polyelectrolyte mixtures on the uniformly charged surface and the charge reversal of the adsorbed layer.We investigated the surface charge density and polyelectrolyte The effect of the valence state of the segment on the adsorption was systematically investigated and it was found that in the absence of small ions in the system, when both polyelectrolyte segments in the system are monovalent, the oppositely charged polyelectrolyte chains on the surface can Adsorbed on the plane, and the surface with the same charge on the surface of the polyelectrolyte and the mutual repulsion between the whole process is the surface charge is oppositely charged with the polyelectrolyte chain charge neutralization process, there is no obvious When the valence state of the polyelectrolyte segment existing as counterion is bivalent, the polyelectrolyte chains with the same charge on the surface can adsorb on the surface, and the phenomenon of charge reversal is obvious. Theoretical studies show that , The electrostatic correlation effect mediated by counterion is one of the main driving forces for multi-layer adsorption of polyelectrolyte mixture.