Unraveling the nanostructures and self-assembly behavior of perfluorosulfonic acid in water/ethanol solvent: Effect of EW and side-chain chemistry

IF 5.4 1区化学 Q2 CHEMISTRY, MULTIDISCIPLINARY

GIANT Pub Date : 2024-08-13 DOI:10.1016/j.giant.2024.100332

Jingnan Song , Suyan Wang , Wutong Zhao , Bonan Hao , Ming Zhang , Yecheng Zou , Gang Wei , Jia Liu , Guangying Chen , Huan Ren , Xuefei Wu , Xuesong Jiang , Yongfeng Zhou , Feng Liu , Yongming Zhang

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Abstract

The perfluorosulfonic acid (PFSA) ionomers are key materials for proton exchange membranes (PEMs) and catalyst layers (CLs). Their morphology is profoundly influenced by the chain assembly behavior of PFSA in dispersions. Hence, we combine the characterization techniques of dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryo-transmission electron microscopy (Cryo-TEM) to study the nanostructures of PFSA dispersions, and provide a structure model for diverse PFSA ionomers in water/ethanol solvent. It is seen that PFSA ionomers self-assembly into a rod-like particle in dilute dispersion. As the concentration increases, the primary rod aggregates gradually assemble into a swollen- or Gaussian-network structure. Beyond this feature, we see that different PFSA ionomers show different nanostructures in dispersion. For the long-side-chain (LSC) PFSA ionomers, the 800-LSC PFSA tends to form monodisperse rod-like aggregates that is in a highly ordered arrangement with a rod diameter of 3.16 nm and a length of 28.72 nm. As the equivalent weight (EW) increases to 960, the poor solubility of the main chains in water/ethanol solvents leads to the “end-to-end” assemblies of the primary rod particles and dendritic secondary aggregates. The short-side-chain (SSC) PFSA ionomer that shares the same backbone with 960-LSC PFSA exhibit remarkable mono-dispersity and ordered arrangement of rod-like aggregates in water/ethanol solvents due to the strong electrostatic repulsion.

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揭示全氟磺酸在水/乙醇溶剂中的纳米结构和自组装行为：EW和侧链化学性质的影响

全氟磺酸（PFSA）离子聚合物是质子交换膜（PEM）和催化剂层（CL）的关键材料。它们的形态深受分散体中 PFSA 链组装行为的影响。因此，我们结合动态光散射（DLS）、小角 X 射线散射（SAXS）和低温透射电子显微镜（Cryo-TEM）等表征技术来研究 PFSA 分散体的纳米结构，并提供了水/乙醇溶剂中各种 PFSA 离子聚合物的结构模型。结果表明，PFSA 离子聚合物在稀释分散液中自组装成杆状颗粒。随着浓度的增加，初级棒状聚集体逐渐组装成膨胀或高斯网状结构。除了这一特征外，我们还发现不同的 PFSA 离子聚合物在分散过程中呈现出不同的纳米结构。对于长侧链（LSC）PFSA 离子聚合物，800-LSC PFSA 倾向于形成单分散棒状聚集体，这种聚集体呈高度有序排列，棒状直径为 3.16 纳米，长度为 28.72 纳米。当等效重量（EW）增加到 960 时，由于主链在水/乙醇溶剂中的溶解性较差，导致主杆状颗粒和树枝状次级聚集体 "端对端 "地组装在一起。与 960-LSC PFSA 具有相同主链的短侧链（SSC）PFSA 离子聚合物由于具有很强的静电排斥力，在水/乙醇溶剂中表现出显著的单分散性和杆状聚集体的有序排列。

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来源期刊

GIANT Multiple-

CiteScore

8.50

自引率

8.60%

发文量

审稿时长

42 days

期刊介绍： Giant is an interdisciplinary title focusing on fundamental and applied macromolecular science spanning all chemistry, physics, biology, and materials aspects of the field in the broadest sense. Key areas covered include macromolecular chemistry, supramolecular assembly, multiscale and multifunctional materials, organic-inorganic hybrid materials, biophysics, biomimetics and surface science. Core topics range from developments in synthesis, characterisation and assembly towards creating uniformly sized precision macromolecules with tailored properties, to the design and assembly of nanostructured materials in multiple dimensions, and further to the study of smart or living designer materials with tuneable multiscale properties.