Electrostatic properties of polyethylene LB films on metal electrodes

Medium-density polyethylene (PE) thin films have been prepared by the Langmuir-Blodgett technique. According to the capacitance measurement, 1/C is proportional to the number of layers, indicating that the layer-by-layer deposition of PE films proceeded successfully. This was also confirmed by the thickness dependence of infrared spectrum. Using the Kelvin probe surface potential measurement, it was concluded that as-deposited PE films were positively charged due to the displacement of electrons from the film to a metal. An energy diagram of the alkane oligomer was computed based on a density functional molecular orbital calculation. Finally the possibility of positive charging of the PE film is discussed.