Interfacial processes during plasma polymer deposition on oxide covered iron

The paper gives an insight into the interfacial processes at the iron oxide/polymer interface during the plasma polymer deposition from hexamethyldisilane ((CH3)(3)SiSi(CH3)(3)). For this purpose an in situ set-up which combines IR-spectroscopy under grazing incidence and quartz crystal micro weighing was used. The deposited plasma polymers had a thickness of less than 10 nm. The surface morphology of the films deposited on flame annealed gold could be visualized by means of atomic force microscopy. The plasma polymers deposited in this study form laterally homogeneous films even at film thicknesses lower than five nanometer. The features of the plasma polymers have a diameter of about 20 nm and a height of about 0.5 nm. During the initial growth of the plasma polymer a formation of covalent bonds at the interface was indicated by IR-spectroscopy. First voltapotential measurements of the plasma modified surface by means of a scanning Kelvin probe show that Fe3+ states in the iron oxide surface are partly reduced to Fe2+ during the formation of the first plasma polymer layers. (C) 1999 Elsevier Science S.A. All rights reserved.