Coatings comprising various volume fractions of particulate polyaniline dispersed in a polyvinylbutyral binder are applied to iron substrates. A scanning Kelvin probe is used to measure substrate potentials in humid air and follow corrosion-driven coating delamination ͑cathodic disbondment͒ when 5% w/v ͑0.86 M͒ aqueous NaCl contacts a coating defect. Emeraldine base has no effect on substrate potential or delamination kinetics. Emeraldine salts ͑ES͒ doped using p-toluenesulfonic ͑HpTS͒, camphorsulfonic ͑HCS͒, phosphoric ͑H 3 PO 4 ͒, and phenylphosphonic ͑H 2 PP͒ acids increase substrate potentials by up to 0.36 V and inhibit delamination with efficiency order of HpTS Ͻ HCS Ͻ H 3 PO 4 Ӷ H 2 PP. Dopant salts added to the corrosive electrolyte do not inhibit delamination. It is proposed that inhibition arises primarily from cathodic O 2 reduction becoming relocated from the ennobled substrate onto the ES coating. However, Fe 3 ͑PO 4 ͒ 2 and FePP salt films formed at the ES-substrate interface also contribute by hindering interfacial electron transfer.

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