Visualization of charge domains on polymer surfaces

The tribo-electric charging of polymers is widely known and applied in many technical processes. However, the molecular and electronic reasons for this phenomenon are not fully understood. In a former work we showed that the tribo-electric charging of polymer particles can be described by their electron pair acceptor and donator properties. But polymer charging cannot be fully explained on a molecular level. During the collision of two particles expanded areas come into contact and an enormous number of molecules is involved in the charge formation process. In the present study, the lateral distribution of charges and their dissipation over the time were investigated using two electric force microscopy techniques (surface potential imaging mode and electric force imaging mode). The recorded images show that oppositely charged domains exist on polymer surfaces side by side. The dissipation of deposited charges depends on the electronic properties of the polymer. Also water adsorbed from the surrounding atmosphere or incorporated in the polymer bulk has a great influence on the charge stability.