Conjugated Polymers as Anticorrosion Layers

Previously, several methods for preventing or controlling corrosion are mentioned. Among these, the application of a surface coating based on an organic material is considered very effective. 

Conjugated polymers (CPs) may have an important role for this latter function. Moreover, these materials provide a potential cheap alternative to chromium and phosphate treatments and their pollution, and can be applied on both ferrous and non-ferrous metals. 

The principal characteristic of CPs is their conductivity. At the neutral state the CP conductivity is typically quite low, ranging from insulating to semiconducting. After a partial oxidation (often referred to as p-doping), these polymers become highly conductive, as a metal. The partial reduction (referred as to n-doping) is possible although hard to maintain, especially in air. 

CPs can be classified into three general types, based on the nature of the p-doping (oxidation) process during polymer synthesis [5]  

All three types of polymers have been and continue to be investigated for use in corrosion control coatings, either directly as a primer coating or surface treatment or as one of the components of conventional coatings. 

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