Abstract
The contact charge developed between powders of a copolymer–ionomer blend and ferrite beads correlates well with the chemical structure of the ions. There is a clear correspondence between the sign of the charge acquired by the blend and the sign of the bonded ion in the ionomer. When both ions are bonded, the charge is small. These charging results support the ion transfer mechanism for charging. The measured charge is less than the value calculated from the total amount of surface ions, and there is a small difference in the magnitude of the charge between the various ionomer blends. A higher charging capacity is observed with the ionomers with a mobile H+, OTs−, or I−, while a lower charging capacity is observed with the pyridinium, Bu4N+, and Na+ ion. This result is attributed to ion pairing which reduces the charging capacity of the ions. It is proposed that only dissociated ions transfer across the contact to produce charge. With this model, it is estimated that only 10% of the ion pairs in the surface water layer are dissociated. This indicates that the ion pair dissociation equilibrium constant in the surface water layer is lower than in bulk water. © 1994, American Chemical Society. All rights reserved.