Triboelectric series generated by simultaneous water dewetting of solids

Abstract

Most solids acquire a negative electrostatic charge when dewetted by pure water, with stronger charging on more hydrophobic materials. Here it is shown that when pairs of polymer slides are simultaneously withdrawn from a pool of pure water, the more hydrophobic slide charges negative, while a sufficiently less hydrophobic counterpart charges positive. The polarity of the charging for different polymer material combinations closely aligns with the triboelectric series. The negative charging of more hydrophobic slides is explained by charging by water dewetting, while the positive charging of the less hydrophobic slide is attributed to biased liquid-contact charging. Based on these findings, a non-frictional solid insulator contact charging mechanism is proposed, driven by asymmetric dewetting of adsorbed water menisci during separation, which provides a unifying explanation for common triboelectric charging characteristics.