Charge transport and glassy dynamics in polymeric ionic liquids as reflected by their inter- and intramolecular interactions.
Charge transport and glassy dynamics in polymeric ionic liquids as reflected by their inter- and intramolecular interactions.
复制标题
DOI：
10.1039/c8sm02135j
复制
发表时间：
2019-02
期刊：
影响因子：
3.4
通讯作者：
F. Frenzel;Pia Borchert;A. Anton;V. Strehmel;F. Kremer
中科院分区：
文献类型：
--
作者：
F. Frenzel;Pia Borchert;A. Anton;V. Strehmel;F. Kremer
聚合物离子液体（PILs）形成一类新型材料，其中离子液体（ILs）的非凡性质与聚合物体系的机械稳定性相结合，使其具有多重应用。在本研究中，宽带介电谱（BDS），傅里叶变换红外光谱（FTIR），AC芯片量热法（ACC）和差示扫描量热法（DSC）相结合，以解开电荷传输和玻璃态动力学之间的相互作用。研究了三种低分子量离子液体及其聚合物对应物的阴离子和阳离子系统变化。对于所有检查样品的电荷传输发生玻璃动力学辅助跳跃传导。与低分子量离子液体相比，聚合物体系的DC电导率的热活化在（样品特定的）温度Tσ0下从Vogel-Fulcher-Tammann-变化为Arrhenius-依赖性。该温度已被广泛讨论，以符合玻璃化转变温度Tg，而一个精细的分析，揭示了Tσ0的所有研究中的PIL在高达80 K更高的值。实际上，在Tσ0以下，PIL中的电荷传输变得更有效-尽管与低分子量侧基相比处于低得多的水平-表明沿着聚合物链的传导路径沿着。通过分析特定IR活性振动的温度依赖性证实了这一点，在Tσ0处显示光谱位置和振子强度的明显变化，而其他分子单元不受影响。这导致识别的电荷传输响应（CTR）以及电荷传输非响应（CTI）部分，并铺平了道路，以精细的分子理解PIL中的导电。
Polymeric ionic liquids (PILs) form a novel class of materials in which the extraordinary properties of ionic liquids (ILs) are combined with the mechanical stability of polymeric systems qualifying them for multifold applications. In the present study broadband dielectric spectroscopy (BDS), Fourier transform infrared spectroscopy (FTIR), AC-chip calorimetry (ACC) and differential scanning calorimetry (DSC) are combined in order to unravel the interplay between charge transport and glassy dynamics. Three low molecular weight ILs and their polymeric correspondents are studied with systematic variations of anions and cations. For all examined samples charge transport takes place by glassy dynamics assisted hopping conduction. In contrast to low molecular weight ILs the thermal activation of DC conductivity for the polymeric systems changes from a Vogel-Fulcher-Tammann- to an Arrhenius-dependence at a (sample specific) temperature Tσ0. This temperature has been widely discussed to coincide with the glass transition temperature Tg, a refined analysis, instead, reveals Tσ0 of all PILs under study at up to 80 K higher values. In effect, below the Tσ0 charge transport in PILs becomes more efficient - albeit on a much lower level compared to the low molecular weight pendants - indicating conduction paths along the polymer chain. This is corroborated by analysing the temperature dependence of specific IR-active vibrations showing at Tσ0 distinct changes in the spectral position and the oscillator strength, whereas other molecular units are not affected. This leads to the identification of charge transport responsive (CTR) as well as charge transport irresponsive (CTI) moieties and paves the way to a refined molecular understanding of electrical conduction in PILs.