Visualization of Two-dimensional Single Chains of Hybrid Polyelectrolytes on Solid Surface

Zhang, LL (Zhang, Lan-Lan)^{[ 1,2 ]} ; Miao, WK (Miao, Wen-Ke)^{[ 1,2 ]} ; Ren, LJ (Ren, Li-Jun)^{[ 1,2 ]} ; Yan, YK (Yan, Yu-Kun)^{[ 1,2 ]} ; Wang, W (Wang, Wei)^{[ 1,2,3 ]}

CHINESE JOURNAL OF POLYMER SCIENCE, 2020

DOI: 10.1007/s10118-021-2520-4

摘要

The polyacidic character of polyoxometalate (POM) clusters endows high ionic conductivity, making these clusters good candidates for solar and fuel cells. Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance. Thus, solution-processable poly(POM)s are expected to be used as key materials in advanced devices. Further understanding of poly(POM)s will optimize the preparation process and improve device performance. Herein, we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy. Compared with traditional polymers, individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants. Thus, cluster aggregates with diverse shapes were observed. Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined, and studying the aggregate shapes revealed the presence of a curved semirigid chain in solution. Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing. Fundamental insight is critical to understanding the formation of poly(POM) films from solutions as key functional materials, especially for fuel and solar cells.