Electrochemical investigation of the coating/substrate interface stability for styrene/acrylate copolymer films applied on iron

Abstract Water-borne n -butyl acrylate (nBA)/styrene (Sty), 2-ethylhexyl acrylate (EHA)/Sty and nBA/EHA/Sty copolymer dispersions were applied on iron to investigate the latex/substrate interface stability. Scanning Kelvin Probe (SKP) studies were performed to detect the progress of cathodic delamination as function of the latex particle composition. The interface stability decreased with increasing polymer glass transition temperature ( T g ) and in the order EHA/Sty > nBA/EHA/Sty > nBA/Sty. The surface energy of the adhesives reflected the SKP results. Electrochemical Impedance Spectroscopy (EIS) was applied to evaluate water uptake of and diffusion kinetics within the polymers. Calculated diffusion coefficients did not change with the T g .