Neutral and n-Doped Conjugated Polymers for Corrosion Control of Aluminum Alloys

摘要

Conjugated polymers (CPs) continue to be of interest for use as components of corrosion control coatings. For aluminum alloys, however, there is controversy and uncertainty regarding the protection mechanism(s), or indeed even whether corrosion protection by a CP is possible. Recent results from our laboratory indicate that, for an aluminum alloy coated with the oxidized form of polypyrrole, a passivation mechanism is not likely and that the dopant release mechanism may not be effective, especially in the presence of oxygen. An alternative approach is to utilize the neutral or reduced (n-doped) form of a conjugated polymer to cathodically protect the alloy and/or to serve as an oxygen scavenging coating. The CP coatings and alloy studied were neutral polypyrrole and neutral and n-doped poly(2,3-dihexylthieno[3,4-b]pyrazine) on AA 2024-T3. Results from the scanning vibrating electrode technique and galvanic coupling measurements are presented to demonstrate the efficacy of this approach.