Smart release corrosion inhibitor pigments based on organic ion-exchange resins

Novel calcium(II) and zinc(II)-exchanged pigments based on cross-linked sulphonated polystyrene (CSP) are used in model polymer coatings to inhibit cathodic disbondment on galvanised steel surfaces. An in situ scanning Kelvin probe (SKP) technique is used to quantify coating delamination rates as a function of pigment volume concentration after applying aqueous sodium chloride to a penetrative coating defect. Both in-coating cation types significantly retard delamination rates compared with the un-pigmented case. The performance of CSP is compared with pigments prepared from inorganic cation exchangers and shown to be less effective when incorporating Zn(II) cations, but superior when Ca(II) is present.

► Corrosion inhibitor pigments were prepared from a polymer-based cation exchange resin.
► Zinc(II) and calcium(II) smart-release pigments were evaluated.
► An in situ scanning Kelvin probe technique was used to quantify corrosion protection.
► Inhibition of organic coating delamination was demonstrated on galvanised steel.
► Coating disbondment rates were compared with other inorganic cation exchange media.