Amphiphilic copolymers as corrosion inhibitors for zinc pigment

Zinc pigments react in aqueous alkaline paint media with the evolution of hydrogen. The corrosion reaction can be inhibited by addition of styrene-maleic acid-acrylic ester copolymers which were synthesized with three different acrylic esters (ethyl, n-butyl, n-hexyl) and two methacrylic esters (n-dodecyl and n-octadecyl). With increasing chain-length of the ester alcohol of the acrylate monomer the corrosion inhibiting effect of the copolymers decreases. This dependence of the corrosion inhibiting effect from chemical structure of the copolymers can be correlated mathematically with the help of a potential function.