Liu Liyan, Wang Fujia, Zhang Boyi, Zhang Ting, Wang Ying, Han Bing
College of Science, Civil Aviation University of China, Tianjin 300300, China.
School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin 300070, China.
ACS Omega. 2025 Apr 27;10(17):17694-17704. doi: 10.1021/acsomega.5c00002. eCollection 2025 May 6.
In this paper, we investigate the effects of multivalent counterion units and linear counterion chains in the self-assembly of polyelectrolyte (PE) copolymers. Both the valent and structural effects of the counterions are discussed. As the valence of counterion units or the length of counterion chains increases, the electrostatic correlations are significantly strengthened. Compared with multivalent counterion units, the linear structure of counterion chains is primarily manifested in two aspects. First, the electrostatic repulsion among the monovalent ions within the counterion chains diminishes near-neighbor electrostatic correlations, resulting in less compact PE coronas and more stretched PE blocks. Second, the linear arrangement of counterions reinforces the remote spatial electrostatic correlations, prompting the formations of ring-like and semiring-like PE coronas. The charge distribution in the PE coronas closely depends on counterion structures. As the counterion valence or length increases, the enhanced electrostatic effects draw more counterions into the inner regions of the PE coronas. The overcompensation of multivalent counterions within the inner regions of the PE coronas results in local charge inversion. The increased absorption of counterion chains not only raises the positive charge in the inner regions but also extends it to the peripheral regions of the PE coronas, thereby reducing the critical interfacial distance required for the transition in the net charge polarity.
在本文中，我们研究了多价抗衡离子单元和线性抗衡离子链在聚电解质（PE）共聚物自组装中的作用。讨论了抗衡离子的价态和结构效应。随着抗衡离子单元的价态或抗衡离子链的长度增加，静电相关性显著增强。与多价抗衡离子单元相比，抗衡离子链的线性结构主要体现在两个方面。首先，抗衡离子链内单价离子之间的静电排斥减弱了近邻静电相关性，导致PE冠层不那么紧密，PE嵌段更伸展。其次，抗衡离子的线性排列加强了远程空间静电相关性，促使形成环状和半环状PE冠层。PE冠层中的电荷分布密切取决于抗衡离子结构。随着抗衡离子价态或长度增加，增强的静电效应将更多抗衡离子吸引到PE冠层的内部区域。PE冠层内部区域多价抗衡离子的过度补偿导致局部电荷反转。抗衡离子链吸收的增加不仅提高了内部区域的正电荷，还将其扩展到PE冠层的外围区域，从而减小了净电荷极性转变所需的临界界面距离。
