Material Transfer and Polarity Reversal in Contact Charging

In touch : The outcome of contact electrification between dielectrics depends not only on the transfer of charge but also on the transfer of material (see picture). Although only minute quantities of materials are being exchanged during contact, they can reverse the polarity of dielectrics. The reported results corroborate the mosaic model and suggest that the observations are because of the mechanical softness/hardness of the materials