Defects drive the tribocharging strength of PTFE: An ab-initio study
Defects drive the tribocharging strength of PTFE: An ab-initio study
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DOI：
10.1016/j.nanoen.2023.108502
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发表时间：
2023-04
期刊：
影响因子：
17.6
通讯作者：
A. Ciniero;G. Fatti;M. Marsili;D. Dini;M. Righi
中科院分区：
文献类型：
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作者：
A. Ciniero;G. Fatti;M. Marsili;D. Dini;M. Righi
如果聚四氟乙烯（PTFE），通常称为特氟龙，与另一种材料接触并摩擦，几乎可以肯定它在收集负电荷方面比它的对应物更有效。这种简单的基本性质被所谓的摩擦电系列所捕获，其中PTFE排名极高，并且根据材料在接触和摩擦时的静电充电能力定性地排序材料。然而，在对材料进行分类时，除了与功函数的松散相关性外，该系列并没有提供对它们的摩擦电强度的解释。事实上，尽管是一个非常熟悉的过程，已知的几个世纪，摩擦充电仍然是难以捉摸的，并没有完全理解。在这项工作中，我们采用密度泛函理论来寻找PTFE摩擦充电强度的起源。我们研究了当原始或有缺陷的PTFE与不同的清洁和氧化金属接触时电荷如何转移。我们的研究结果表明，在增强电荷转移的缺陷所发挥的重要作用。有趣而出乎意料的是，我们的结果表明，如果稍微弯曲，带负电荷的链比中性链更稳定。事实上，变形可以很容易地促进聚合物，如PTFE，特别是在摩擦接触。这些结果表明，在设计材料的摩擦电性能，其缺陷的特性可能是一个性能决定因素。
If polytetrafluoroethylene (PTFE), commonly known as Teflon, is put into contact and rubbed against another material, almost surely it will be more effective than its counterpart in collecting negative charges. This simple, basic property is captured by the so called triboelectric series, where PTFE ranks extremely high, and that qualitatively orders materials in terms of their ability to electrostatically charge upon contact and rubbing. However, while classifying materials, the series does not provide an explanation of their triboelectric strength, besides a loose correlation with the workfunction. Indeed, despite being an extremely familiar process, known from centuries, tribocharging is still elusive and not fully understood.In this work we employ density functional theory to look for the origin of PTFE tribocharging strength. We study how charge transfers when pristine or defective PTFE is put in contact with different clean and oxidized metals. Our results show the important role played by defects in enhancing charge transfer. Interestingly and unexpectedly our results show that negatively charged chains are more stable than neutral ones, if slightly bent. Indeed deformations can be easily promoted in polymers as PTFE, especially in tribological contacts. These results suggest that, in designing materials in view of their triboelectric properties, the characteristics of their defects could be a performance determining factor.