SURFACE-POTENTIAL MAP OF CHARGED IONOMER POLYMER BLENDS STUDIED WITH A SCANNING KELVIN PROBE

The contact charging of ionomer-polymer blends was studied by the scan ning Kelvin probe. The blends which contain ionomers with mobile ions produced a strong change in its surface potential after contact with a n unbiased Pt/Ir tip. The signal on the contacted area decayed slowly with time. The decay was more rapid with the films containing more ion s. The magnitude of the charge in the surface potential was found to s cale linearly with the film thickness indicating that the charge is lo calized near the surface. In contrast, only a very weak signal was pro duced with the films which contained no ions or no mobile ions (e.g., films with both ions covalently bonded to the polymer). These results support previous reports that ion transfer is important in contact cha rging and the proposal that the resulting charge is primarily a surfac e phenomenon.