Charge transfer in metal/polymer contacts
Charge transfer in metal/polymer contacts
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金属/聚合物接触中的电荷转移
DOI：
10.1088/0022-3727/20/5/002
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
J. Lowell
中科院分区：
文献类型：
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作者：
A. R. Akande;J. Lowell
作者研究了聚合物与金属的接触电荷，特别注意了样品表面不同位置和不同样品之间电荷转移的变化。对于大多数聚合物，他们发现电荷转移不受提纯尝试的影响，以完全不同的方式制备的样品也是如此，他们得出结论，电荷转移是聚合物的固有属性，通常不受偶然杂质等的存在的影响。然而，有一个例外：向聚四氟乙烯的电荷转移似乎是由物理损伤决定的。对于某些聚合物，电荷转移倾向于随着接触金属功函数的增加而增加，但这种趋势并不普遍；向某些聚合物的电荷转移对金属功函数不敏感。(它们表明，这适用于多个触点、滑动触点以及单个非滑动触点。)不同聚合物的表观电荷密度差异非常小，这意味着引起接触带电的电子态密度对于大范围的聚合物来说是基本相同的。然而，解释观察到的电荷密度所需的态密度比本征态的密度要小得多，例如‘悬挂’化学基团的轨道，并且太小，不能在分离过程中允许显著的反隧穿。这些观察结果不能令人满意地与当前的电荷转移模型相一致，这些模型假定金属和聚合物中的局域态之间的电子交换，除非能够可信地识别足够低密度的本征态。
The authors have investigated the contact charging of polymers by metals, paying particular attention to the variation of charge transfer from place to place on the sample surface, and from one sample to another. For most polymers they find that charge transfer is unaffected by attempts at purification and is much the same for samples prepared in quite different ways, and they conclude that charge transfer is an intrinsic property of polymers, not normally dominated by the presence of accidental impurities etc. There is one exception however: charge transfer to PTFE appears to be determined by physical damage. For some polymers the charge transfer tends to increase as the work function of the contacting metal increases but this tendency is not universal; charge transfer to some polymers is insensitive to the metal work function. (They show that this is true for multiple contacts and for sliding as well as for single non-sliding contacts.) The apparent charge density shows remarkably little variation from one polymer to another, and this implies that the density of the electron states responsible for contact electrification is much the same for a wide range of polymers. However, the density of states required to account for the observed charge densities is much smaller than the density of intrinsic states, such as the orbitals of 'pendant' chemical groups, and too small to allow significant back-tunnelling during separation. The observations cannot be satisfactorily reconciled with current models of charge transfer which assume electron exchange between the metal and localised states in the polymer unless intrinsic states of sufficiently low density can be plausibly identified.