Stability and temporal decay of nanopatterned tribocharge on nanotextured elastomer surfaces

摘要

Contact electrification of nanotextured elastomer surfaces often generates nanopatterned tribocharges that are useful for both scientific and practical purposes. For sustained utilization of the nanopatterned tribocharge, their stability and temporal behavior must be characterized and studied. It is, however, a highly challenging task as it requires long-term, repeated probing of the tribocharge at the nanoscale spatial resolution. In this work, we performed such a comprehensive experimental study of nanopatterned tribocharges on elastomer surfaces using Kelvin probe force microscopy (KPFM) and electrostatic force microscopy (EFM). Curve-fitting analysis of the KPFM results not only affirmed the temporally decaying nature of the tribocharge but also separated them into two distinct, fast and slowly decaying, components that could be attributed to two different tribocharging mechanisms. Through pre-constrained optimization of the curve-fitting parameters and comparison of the results, we could attribute the fast and slow decay components to the tribocharges generated by tangential sliding and surface-normal separation of the material interface, respectively. The analysis also enabled us to estimate time-invariant "pedestal" potentials from the KPFM results and predict the existence of long-term stable tribocharge on the nanotextured elastomer surface. We experimentally confirmed it by re-scanning the specimens 14 days after the initial measurements. The observations, analysis, and the mechano-triboelectric charging model will benefit not only the researchers of nanoscale tribocharges but also those interested in the study and applications of triboelectricity in general.