Bombardment induced ion transport - part IV: ionic conductivity of ultra-thin polyelectrolyte multilayer films.
Bombardment induced ion transport - part IV: ionic conductivity of ultra-thin polyelectrolyte multilayer films.
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DOI：
10.1039/c5cp04004c
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发表时间：
2016-02
期刊：
影响因子：
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通讯作者：
Veronika Wesp;M. Hermann;M. Schäfer;Jonas Hühn;W. Parak;K. Weitzel
中科院分区：
文献类型：
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作者：
Veronika Wesp;M. Hermann;M. Schäfer;Jonas Hühn;W. Parak;K. Weitzel
用低能轰击诱导离子输运（BIIT）方法研究了超薄PEM膜的离子电导随温度和层数的变化规律。为此，交替的聚（4-苯乙烯磺酸钠）（PSS）和聚（烯丙胺盐酸盐）（PAH）层的多层沉积在金属电极上，随后由低能钾离子束轰击。离子根据电扩散定律通过膜朝向接地的背侧电极传输。它们在聚合物膜和金属电极之间的界面处被中和。检测到的中和电流与离子束的加速电位成线性比例，表明（PAH/PSS）x多层的欧姆行为，其中x表示双层的数量。电导表现出非单调依赖于双层的数目，x。当2 ≤ x ≤ 8时，电导随双层膜数的增加呈非线性增加。当x ≥ 8时，电导随双层数的增加而减小.的电导的变化是合理的模型占的电导率的结构依赖性。已被测量的电导的最薄的样品是由界面主导的单双层反射特性。离子输运的活化能为0.49 eV。
The dependence of the ionic conductance of ultra-thin polyelectrolyte multilayer (PEM) films on the temperature and the number of bilayers has been investigated by the recently developed low energy bombardment induced ion transport (BIIT) method. To this end multilayers of alternating poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) layers were deposited on a metal electrode and subsequently bombarded by a low energy potassium ion beam. Ions are transported through the film according to the laws of electro-diffusion towards a grounded backside electrode. They are neutralized at the interface between the polymer film and the metal electrode. The detected neutralization current scales linearly with the acceleration potential of the ion beam indicating Ohmic behavior for the (PAH/PSS)x multilayer, where x denotes the number of bilayers. The conductance exhibits a non-monotonic dependence on the number of bilayers, x. For 2 ≤ x ≤ 8 the conductance increases non-linearly with the number of bilayers. For x ≥ 8 the conductance decreases with increasing number of bilayers. The variation of the conductance is rationalized by a model accounting for the structure dependence of the conductivity. The thinnest sample for which the conductance has been measured is the single bilayer reflecting properties dominated by the interface. The activation energy for the ion transport is 0.49 eV.