聚电解质单链在盐溶液中构象转变的并行回火蒙特卡罗研究

发布时间：2018-03-20 15:21

  本文选题：聚电解质　切入点：塌缩　出处：《高分子学报》2017年12期 　论文类型：期刊论文

【摘要】：采用并行回火蒙特卡罗方法,研究了聚电解质单链在盐溶液中的构象转变以及离子的凝聚行为.对不同盐浓度以及不同价态的情况,得到了链均方回转半径(Rg2)随Bjerrum长度lB的变化曲线.模拟结果表明,在不同浓度与价态的盐溶液中,随着lB的增加,链先伸展,然后收缩,最终形成塌缩态.链尺寸受盐浓度与价态的影响,在中等lB范围内,随着单价盐的加入,Rg2逐渐减小.而加入少量的高价盐则会引起Rg2更加显着得减小,这主要是由于高价反离子的凝聚造成的.对于高价盐,在一定的lB范围内,随着盐浓度的增加,存在Rg2先减小后增大的现象.在高价(如二价或三价)盐溶液中,当高价反离子的总电量大于链电量时,高价反离子和共离子(与链带同种电荷的离子)都发生凝聚,而单价反离子几乎不发生凝聚;并且存在高价离子过度补偿引起的链有效电荷反转.
[Abstract]:A parallel tempering Monte Carlo method was used to study the conformation transition of polyelectrolyte single chain in salt solution and the condensation behavior of ions. The curve of chain mean square radius of rotation (Rg2) with the length of Bjerrum is obtained. The simulation results show that in salt solutions with different concentrations and valence states, the chain expands first and then shrinks with the increase of LB. The chain size was affected by the concentration and valence of salt and gradually decreased with the addition of monovalent salt Rg2. However the addition of a small amount of high salt would result in a more significant decrease of Rg2. This is mainly caused by the condensation of high valence counter ions. In a certain range of lb, with the increase of salt concentration, Rg2 decreases first and then increases. In the solution of high valence salt (such as divalent or trivalent), When the total charge of the high valence counter ion is larger than the chain charge, both the high valence counter ion and the common ion (with the same charge as the chain charge) are condensed, while the univalent counter ion is almost not condensed. And there is the chain effective charge reversal caused by the overcompensation of high valence ions.
【作者单位】： 南开大学物理科学学院;
【基金】：国家自然科学基金(基金号21574071,21528401,20925414,91227121) 教育部创新团队发展计划(项目号IRT1257) 高等学校学科创新引智计划(项目号B16027)资助
【分类号】：O631
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本文编号：1639660