The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes.
The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes.
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DOI：
10.1039/c5sm01184a
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发表时间：
2015-09
期刊：
影响因子：
3.4
通讯作者：
Yanpu Zhang;E. Yıldırım;H. Antila;Luis D. Valenzuela;M. Sammalkorpi;J. Lutkenhaus
中科院分区：
文献类型：
--
作者：
Yanpu Zhang;E. Yıldırım;H. Antila;Luis D. Valenzuela;M. Sammalkorpi;J. Lutkenhaus
聚电解质复合物（佩奇）通过将聚阳离子和聚阴离子溶液混合在一起而形成，并且已经被探索用于各种应用。PEC加工和应用的一个挑战是，在某些条件下，所形成的佩奇在数分钟至数天的过程中聚集并从悬浮液中沉淀出来。这种聚集受几个因素如静电排斥、货车范德华吸引力和疏水相互作用控制。在这项工作中，我们探讨了胶体稳定和不稳定的复合物之间的边界，因为它是由聚阳离子/聚阴离子混合比和离子强度的影响。研究的聚合物是聚（二烯丙基二甲基氯化铵）（PDAC）和聚（4-苯乙烯磺酸钠）（PSS）。物理性质，如浊度，流体动力学尺寸，和zeta电位进行了研究后，复杂的形成。我们还进行了详细的分子动力学模拟，以检查在不同的混合比和盐浓度的佩奇的结构和有效电荷分布，以支持实验结果。结果表明，胶体稳定/不稳定的边界可能标志着从添加盐的屏蔽效应，导致弱电荷的复合物的聚集。在较高的盐浓度下，络合物最初形成，然后逐渐溶解到溶液中。
Polyelectrolyte complexes (PECs) form by mixing polycation and polyanion solutions together, and have been explored for a variety of applications. One challenge for PEC processing and application is that under certain conditions the as-formed PECs aggregate and precipitate out of suspension over the course of minutes to days. This aggregation is governed by several factors such as electrostatic repulsion, van der Waals attractions, and hydrophobic interactions. In this work, we explore the boundary between colloidally stable and unstable complexes as it is influenced by polycation/polyanion mixing ratio and ionic strength. The polymers examined are poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate) (PSS). Physical properties such as turbidity, hydrodynamic size, and zeta potential are investigated upon complex formation. We also perform detailed molecular dynamics simulations to examine the structure and effective charge distribution of the PECs at varying mixing ratios and salt concentrations to support the experimental findings. The results suggest that the colloidally stable/unstable boundary possibly marks the screening effects from added salt, resulting in weakly charged complexes that aggregate. At higher salt concentrations, the complexes initially form and then gradually dissolve into solution.