Molecular Dynamics and Charge Transport in Highly Conductive Polymeric Ionic Liquids
Molecular Dynamics and Charge Transport in Highly Conductive Polymeric Ionic Liquids
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DOI：
10.1021/acs.macromol.7b00554
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发表时间：
2017-05-23
期刊：
影响因子：
5.5
通讯作者：
Kremer, Friedrich
中科院分区：
文献类型：
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作者：
Frenzel, Falk;Guterman, Ryan;Kremer, Friedrich
采用宽频率(10（-2)-10(7)Hz）和温度范围（100-400 K）的宽带介电光谱（BDS）和DSC- ac芯片量热法研究了不同分子量（9700、44200、51600和99500 g/mol）的聚[3（2-甲氧基乙氧基）乙基丙烯氧基磺酸铵]（PAAPS）聚合物离子液体的玻璃动力学和电荷输运。介电光谱的特征是(i)弛豫过程，（ii）电荷输运和（iii）电极极化的叠加。弛豫过程(i)分配给动态玻璃化转变和二次弛豫。电荷输运（ii）可以用Dyre等人的随机自由能势垒模型来描述；巴顿-纳米川-中岛（BNN）关系在过去的80多年里得到了很好的发展。电极极化（iii）遵循Serghei等人分析的特征，在低频侧存在偏差。动态玻璃跃迁弛豫速率与载流子跳变速率之间的比例关系反映了玻璃跃迁辅助跳变的电荷输运性质。因此，所研究的PIL暴露了迄今为止在100℃以下这类材料中观察到的最高直流电导率值；并且首次发现电导率随聚合度的增加而增加。将所研究的聚合物离子液体与其他聚合物离子液体进行比较，对新型高导电性离子液体的设计有一定的启示。
Glassy dynamics and charge transport are studied for the polymeric ionic liquid (PIL) poly[tris(2-(2-methoxyethoxy)ethyl)ammonium acryloxypropyl sulfonate] (PAAPS) with varying molecular weight (9700, 44200, 51600, and 99500 g/mol) by broadband dielectric spectroscopy (BDS) in a wide frequency (10(-2)-10(7) Hz) and temperature range (100-400 K) and by DSC- and AC-chip calorimetry. The dielectric spectra are characterized by a superposition of (i) relaxation processes, (ii) charge transport, and (iii) electrode polarization. The relaxation processes (i) are assigned to the dynamic glass transition and a secondary relaxation. Charge transport (ii) can be described by the random free-energy barrier model as worked out by Dyre et al.; the Barton-Namikawa-Nakajima (BNN) relationship is well fulfilled over more than 8 decades. Electrode polarization (iii) follows the characteristics as analyzed by Serghei et al., with deviations on the low frequency side. The proportionality between the relaxation rate of the dynamic glass transition and the charge carrier hopping rate reflects the nature of charge transport as glass transition assisted hopping. Hereby, the PIL under study exposes the highest dc conductivity values observed for this class of materials below 100 degrees C, so far; and for the first time a conductivity increase by rising degree of polymerization. The comparison of the polymeric ionic liquids under study with others implies conclusions on the design of novel highly conductive PILs.