Mechanism of triboelectricity: a novel perspective for studying contact electrification based on metal-polymer and polymer-polymer interactions

Abstract

The static electricity that is generated when two identical or different materials come in contact with each other and separated is a well known physical phenomenon that has been studied for over 25 centuries. Contact charging occurs in technological and natural aspects of our everyday life. Generation of lightning and the feeling of unexpected shocks on dry days are excellent examples of naturally occurring phenomenon, while in technology it is used for photocopying and laser printing. Owing to the increase in energy consumption around the globe and demand for carbon emissions free energy sources, the triboelectric effect has recently being utilized as an e ffective means of harvesting mechanical energy and converting it into electricity for novel applications like powering portable electronic devices and self powered active sensing. Despite the fact that it has been known and applied for many years, the fundamental mechanism of contact electrification is still not fully understood. This study proposes a mechanism for triggering such triboelectric charge based on polymer-polymer and metal-polymer interactions. Conventionally, the mechanism of electrostatic charge generation is being presumed as a process giving rise to a combination of positive (arising from contact) and negative (arising from separation) charges in every single contact and separation. However, in our mechanism we propose a concept that shows combination of both positive and negative charges as \contact" and either positive or negative charge, depending on the initial contact-charge polarity of the material (due to surface charge mosaic), as \separation" charge. Different kinds of polymers like polydimethylsiloxane (PDMS), polytetra uoroethylene (PTFE), Polyethersulfone (PES) and polypropene (PP) were used in this study and similar characteristic was observed for all of the polymers. Thus, our perception of the working principle of triboelectri cation between two dielectric materials or a metal and a dielectric material is consistent and potentially vital in comprehending some unresolved controversies on triboelectricity.