BINDING BEHAVIOR OF ORGANIC MONOMERS ON IRON SURFACES AND CORROSION OF THE RESULTANT CHEMICALLY MODIFIED SURFACES

In this study a new concept is discussed, to anchor polymers onto metal surfaces by primary chemical bonds. Organic molecules with two functional groups are positioned between polymer and substrate, which should be bonded to reactive centers of the metal surface by one functional group and to the polymer by conventional C-C bonds. As a first in this direction, the reaction between simple aliphatic mercaptanes and iron surfaces has been studied in detail. Surface analytical investigations have proven, that mercaptane molecules can be bonded to metallic clean iron surfaces by Fe-S-R bonds. The reaction itself has to be performed under well controlled electro-chemical conditions. The stability of the bonds is quite large as well in air as in many different electrolytes. The stability is limited by a prolonged oxygen reduction at large cathodic overpotentials. Probably, the mercaptane molecules are chemically oxidised by the H2O2 formed during the reduction of oxygen and the resulting sulfonic acid desorbs from the electrode surface.