Decoupling Segmental Dynamics and Ionic Transport for Superionic Anhydrous Proton Conductors of Polyoxometalate-poly(ethylene glycol) Nanocomposites
Decoupling Segmental Dynamics and Ionic Transport for Superionic Anhydrous Proton Conductors of Polyoxometalate-poly(ethylene glycol) Nanocomposites
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多金属氧酸盐-聚乙二醇纳米复合材料超离子无水质子导体的解耦链段动力学和离子输运
DOI：
10.1002/marc.202200227
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发表时间：
2022
影响因子：
4.6
通讯作者：
Yin Panchao
中科院分区：
文献类型：
--
作者：
Zheng Zhao;Li Mu;Lai Yuyan;Cao Youjin;Yin Panchao
在“盐中聚合物”体系中，纳米级聚氧乙烯酸盐（POM）和聚乙二醇（PEG）的络合可以获得无水质子导体。H+浓度的增加和POM间距的缩短有利于降低H+跳跃的能垒。将具有相同结构/尺寸（约1 nm）但不同电荷密度的POM分别与PEG络合，浓度范围为10至60重量%。随着POM电荷密度的增加，由于POM对PEG基底的限制强度增加，可以观察到粘度增加的趋势。进一步应用分数瓦尔登规则分析了PEG-POM纳米复合材料的粘度与质子传导率的关系，揭示了PEG-POM纳米复合材料质子传导的微观机理：1）当POM浓度为10 ~ 30% wt时，离子传输与聚合物链动力学密切相关; 2)对于40 - 60wt%的浓度范围，离子传导在很大程度上与聚合物基体的链动力学分离。随着瓦尔登图转移到超离子区。质子传输与聚合物链段动力学的解耦允许纳米复合材料的机械性能和质子传导的同时增强，为具有集成功能的无水质子导体的合理设计提供指导。
Superionic anhydrous proton conductors can be obtained from the complexation of nanoscale polyoxometalates (POMs) and poly(ethylene glycol) (PEG) in the “polymer in salt” regime. The reduced energy barrier of H+ hopping is facilitated from the increased H+ concentration and shortened inter-POM distances. POMs with identical structure/size (≈1 nm) but different charge densities are complexed with PEG, respectively, with concentrations ranging from 10 to 60 % wt. Increasing trends of viscosities can be observed with the rising charge densities of POMs due to the increasing confinement strength on PEG substrate from POMs. Fractional Walden rule is further applied to analyze the viscosity and proton conductivity correlations, and microscopic mechanisms of proton conduction for PEG-POM nanocomposites are revealed: 1) ion transport is highly associated with polymer chain dynamic for POMs concentrations ranging from 10 to 30 % wt.; 2) ionic conduction is largely decoupled from chain dynamic of polymer matrix for concentrations ranging from 40 to 60 % wt. with Walden plots shifted to the superionic regime. The decoupling of proton transport from polymer segment dynamics allows the simultaneous enhancements of the nanocomposites’ mechanical properties and proton conductions, providing guidelines for the rational design of anhydrous proton conductors with integrated functionalities.