Microscopic Mechanisms and Surface Adaptation Effects in Slide-Electrification

滑动带电的微观机制和表面适应效应

• 批准号: 505838636
• 负责人: Dr. Denis Andrienko
• 金额: --
• 依托单位: Max-Planck-Institut für Polymerforschung
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/505838636?language=en
• 关键词: Microscopic; Mechanisms; Surface; Adaptation; Effects

Slide electrification describes a spontaneous charge separation between a moving liquid droplet and a hydrophobic surface. Depending on substrate material and liquid, the drop accumulates either positive or negative charge with the substrate charging oppositely. Here, the drop charge can be influenced by the contact time between surface and water drop and the time between subsequent drops. Models, that describe the charge generation, therefore include a surface adaptation term, very much akin to wetting adaptation phenomena. The microscopic origin of slide electrification and the surface adaptation effects is still unclear. The mechanism has been rationalized phenomenologically, assuming charge pinning at the receding contact line. Here, electron transfer, adsorption/desorption of ions, or an incomplete reorganization of the electric double layer could all lead to the observed effects. Thus, the first goal of our project is a molecular understanding of slide electrification. We will combine experiments with computer simulations and systematically change the solid-liquid interface by varying the three components that are involved: 1) the substrate, 2) the hydrophobic layer 3) and the liquid (type of liquid, salt concentration, pH). For the substrate, the dielectric permittivity and surface chemistry are the important factors contributing to slide electrification. To investigate the contribution of ionic and electronic charge transfer to the slide electrification process, we will also include carbon-based model surfaces with defined electronic conductivity. To control the grafting density and the charge diffusion at the surface, we will change the molecular weight of the hydrophobic layer and the surface roughness. In addition, we will vary the surface chemistry, e.g. with hydroxide and amine functionalized surfaces. To study the interplay between wetting adaptation and charge adaptation, we will study adaptive polymeric and polyelectrolyte surfaces in cooperation with other groups within this SPP. Thus, we want to clarify the mechanisms behind the voltage that forms at the three-phase contact line and the surface adaptation. The application of slide electrification is electricity generation, a potential source of renewable energy. Currently, the efficiency of energy conversion from kinetic droplet energy to electric power is very low: much less than 0,1 %. Therefore, the second goal of the project is to understand the fundamental limits of the slide electrification efficiency. We want to identify substrate – surface layer – liquid combinations that yield improved conversion efficiencies. This will be achieved by computational pre-screening of surface combinations, aiming at those that maximize the surface voltage and the drop charge. The top performing combinations will be then characterized experimentally.

载玻片带电描述了移动的液滴和疏水表面之间的自发电荷分离。取决于基底材料和液体，液滴积累正电荷或负电荷，基底带相反电荷。在此，液滴电荷可受表面与水滴之间的接触时间以及后续液滴之间的时间影响。因此，描述电荷产生的模型包括表面适应项，非常类似于润湿适应现象。滑动带电的微观起源和表面适应效应尚不清楚。该机制已合理化的现象，假设在后退接触线的电荷钉扎。在这里，电子转移，离子的吸附/解吸，或双电层的不完全重组都可能导致观察到的效果。因此，我们项目的第一个目标是对幻灯片带电的分子理解。我们将联合收割机实验与计算机模拟相结合，并通过改变所涉及的三个组件来系统地改变固液界面：1）基底，2）疏水层3）和液体（液体类型，盐浓度，pH值）。对于基底，介电常数和表面化学性质是导致滑动带电的重要因素。为了研究离子和电子电荷转移对载玻片带电过程的贡献，我们还将包括具有定义的电子电导率的碳基模型表面。为了控制接枝密度和电荷在表面的扩散，我们将改变疏水层的分子量和表面粗糙度。此外，我们还将改变表面化学性质，例如氢氧化物和胺官能化表面。为了研究润湿适应和电荷适应之间的相互作用，我们将与SPP内的其他组合作研究自适应聚合物和聚合物表面。因此，我们希望澄清在三相接触线和表面适应形成的电压背后的机制。滑动电气化的应用是发电，这是一种潜在的可再生能源。目前，从液滴动能到电能的能量转换效率非常低：远低于0.1%。因此，该项目的第二个目标是了解滑道电气化效率的基本限制。我们想找出能提高转换效率的基质-表面层-液体组合.这将通过表面组合的计算预筛选来实现，目标是使表面电压和液滴电荷最大化。然后将通过实验表征表现最佳的组合。