Organic molecules differing in the type of backbone and anchor group as corrosion inhibitors for aluminum

Organic compounds, added in a small amount to corrosive solution, have been used for decades as inhibitors of metal corrosion. Usually, the organic compound is chemisorbed on the metal surface thus forming a protective layer which is able to retard the metal dissolution. This system is quite complex and the final result, i.e. the level of protectiveness, depends on the properties of organic molecule, properties of the substrate and of the corrosive medium. Experimental efforts in the past decades have accumulated large amounts of research evidence for the protectiveness of various systems but there is still no simple method to predict how an organic molecule would perform on a selected metal. This work therefore addresses the basic relationships between aluminum surfaces and corrosion inhibitors. To achieve that, we first designed a series of organic compounds which differed in the (a) type of backbone chain (alkyl and perfluoro), (b) length of backbone chain, and (c) type of anchor group. Thereafter, the experiments were utilized in such a way to allow the investigation of the effect of the inhibitor's anchor group and the backbone chain on their performance against corrosion of aluminum in chloride solution.