Solid-to-Liquid Phase Transition in Polyelectrolyte Complexes
Solid-to-Liquid Phase Transition in Polyelectrolyte Complexes
复制标题
聚电解质复合物中的固-液相变
DOI：
10.26434/chemrxiv.12121086
复制
发表时间：
2020
期刊：
影响因子：
5.5
通讯作者：
M. Tirrell
中科院分区：
文献类型：
--
作者：
Siqi Meng;Jeffrey M. Ting;Hao;M. Tirrell
已知强相互作用的聚电解质络合物(PECs)可形成固体
加入盐后可转变为液滴的沉淀物，以打破固有
离子缔合。然而，这种相变的起源和分子细节
人们对固体复合体的构成仍然知之甚少。在这里，我们全面研究
盐驱动的模型对称PEC体系的固-液相变
两种苯乙烯类聚电解质的动力学、相行为和内部结构
结构。在无盐状态下，流变学和热重测量表明
这种PEC看起来是一种软固体，按重量计含90%的水。但是，有了
逐步添加高达2.0M的NaBr盐，令人惊讶地从103左右坚硬到105
PA模数，并将水排入上清液。利用小角X射线散射和
低温透射电子显微镜，我们确定了违反直觉的盐-
硬化和失水行为可归因于聚电解质的结构演变
络合相中的链，其中盐掺杂松弛紧密盘绕并高度溶剂化
聚集的球形聚集体和暴露的原本隐藏的疏水结构域。在一个
大约2.5M的NaBr值，PECS转变为粘弹性液体，以及
聚电解质链重排成更均匀的梯状结构。在液体中
在此条件下，进一步添加盐可以使链条松弛更快，并使材料略有软化。
在这个多功能的电荷驱动系统中访问的材料属性的广度给出了新的
对如何更好地利用物理的离子和化学属性的预测性见解
在功能性PEC材料中的性能。
Strongly interacting polyelectrolyte complexes (PECs) are known to form solid
precipitates that can transform into liquid droplets upon the addition of salt to break intrinsic
ionic associations. However, the origin of this phase transition and the molecular details of
what constitutes a solid complex remain poorly understood. Here, we study comprehensively
the salt-driven solid-to-liquid phase transition of a model symmetric PEC system formed by
two styrenic polyelectrolytes, from the perspectives of dynamics, phase behavior, and internal
structures. In the salt-free state, rheological and thermogravimetric measurements revealed that
this PEC appeared to be a soft solid comprising 90 % water by weight. However, with
progressive addition of up to 2.0 M NaBr salt, it surprisingly stiffened from around 103 to 105
Pa in modulus and expelled water into the supernatant. Using small-angle X-ray scattering and
cryogenic transmission electron microscopy, we determined that the counterintuitive salt-
stiffening and water loss behaviors can be ascribed to the structural evolution of polyelectrolyte
chains in the complex phase, in which salt doping loosened tightly coiled and highly solvated
clusters of spherical aggregates and exposed otherwise-hidden hydrophobic domains. At an
approximate 2.5 M NaBr threshold, the PECs transformed into a viscoelastic liquid, and
polyelectrolyte chains rearranged into more homogenous ladder-like structures. In the liquid
regime, further salt addition enabled faster chain relaxation and slightly softened the materials.
The breadth of material properties accessed in this versatile, charge-driven system gives new
predictive insights into how to harness better ionic and chemical attributes toward physical
performance in functional PEC materials.
登录
查看更多内容
影响因子：
18.2
作者：
Lytle, Tyler K.;Chang, Li-Wei;Sing, Charles E.
通讯作者：
Sing, Charles E.
影响因子：
15.6
作者：
Veis A
通讯作者：
Veis A
影响因子：
5.7
作者：
McCarty, James;Delaney, Kris T.;Shea, Joan-Emma
通讯作者：
Shea, Joan-Emma
影响因子：
41.2
作者：
Zhao Q;Lee DW;Ahn BK;Seo S;Kaufman Y;Israelachvili JN;Waite JH
通讯作者：
Waite JH