Contact electrification polarity of polyethylene particles: A morphology‐derived anomalous size dependence

Abstract

AbstractThe size dependence of contact electrification (CE) for the same material particles is a common but poorly understood phenomenon. Generally, smaller particles acquire negative charges and larger particles positive charges. However, we discover that polyethylene particles can exhibit the opposite polarity under certain conditions. We demonstrate that the particle morphology, such as sphericity and surface roughness, plays a crucial role in determining the polarity, with more spherical and smoother particles being positively charged. This morphology effect can even alter the relative positions of materials in the triboelectric series. We propose a model that incorporates both the morphology and size effects to explain CE of the same material particles. The model successfully reproduces all our experimental results and predicts a nontrivial cyclic triboelectric sequence that we further confirm experimentally. This article reveals new insights into the nonequilibrium charge transfer mechanisms in CE.