Electrochemical oxidation of ethylenediamine: New way to make polyethyleneimine-like coatings on metallic or semiconducting materials

A mechanism is proposed for the anodic polymerization of ethylenediamine (E DA). Initially, there occurs the formation of the radical cation NH2CH2CH2N H2+. followed by the breaking of the C-N bond, the expulsion of NH2., and c oncomitant formation of the primary carbocation NH2CH2CH2+ or the aziridini um cation. This cation reacts with an NH2 group of an EDA molecule, yieldin g a new amine which can be further oxidized. The product on the anode is a polyethyleneimine like polymer. A similar product was found for diethylenet riamine, whose oxidation was studied too. Other pure omega-amines can also polymerize if they are primary amines and have vicinal alkyl groups which a re secondary, i.e., have the formula NH2CH2RCH2NH2. (C) 2000 The Electroche mical Society. S0013-3651(99)01-106-3. All rights reserved.