Šutka Andris, Mālnieks Kaspars, Lapčinskis Linards, Timusk Martin, Kalniņš Kaspars, Kovaļovs Andrejs, Bitenieks Juris, Knite Māris, Stevens Daniel, Grunlan Jaime
Research Laboratory of Functional Materials Technologies, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Paula Valdena 3/7, 1048 Riga, Latvia.
Phys Chem Chem Phys. 2020 Jun 21;22(23):13299-13305. doi: 10.1039/d0cp01947j. Epub 2020 Jun 8.
Polymer contact electrification offers the possibility to harvest mechanical energy using lightweight, flexible and low-cost materials, but the mechanism itself is still unresolved. Several recent studies confirm heterolytic covalent bond breaking as the mechanism for surface charge formation. Here it is shown that the reason for the formation of surface charge by contacting two identical polymers results from the fluctuation in the surface irregularities, and that contacted materials with a greater porosity or surface roughness differential result in a greater generation of surface charge. Porosity and surface roughness create uneven surface length percentage changes in the lateral direction during deformation, which changes the charge density across the surface during relaxation. Multilayered membranes exhibit flexoelectric properties upon pressing and releasing by generating charge without separating individual membrane layers. This new insight deepens the understanding of polymer contact electrification and highlights better ways to prepare triboelectric or flexoelectric nanogenerator devices.
聚合物接触起电提供了使用轻质、柔性且低成本材料来收集机械能的可能性，但该机制本身仍未得到解决。最近的几项研究证实，异裂共价键断裂是表面电荷形成的机制。本文表明，通过接触两种相同聚合物形成表面电荷的原因是表面不规则性的波动，并且具有更大孔隙率或表面粗糙度差异的接触材料会产生更多的表面电荷。孔隙率和表面粗糙度在变形过程中会在横向产生不均匀的表面长度百分比变化，这会在松弛过程中改变整个表面的电荷密度。多层膜在按压和释放时会通过产生电荷而不分离单个膜层来表现出挠曲电特性。这一新见解加深了对聚合物接触起电的理解，并突出了制备摩擦电或挠曲电纳米发电机装置的更好方法。
