Direct evidence of early blister formation in polymer-coated metals from exposure to chloride-containing electrolytes by alternating-current scanning electrochemical microscopy

Abstract

This work contributes to establish the development of an early specific effect of chloride ions in defect-free coated metals leading to the heterogeneous swelling at the metal-polymer interface. Frequency-dependent alternating-current scanning electrochemical microscopy (AC-SECM) was successfully applied to visualize spatially-resolved differences in the topography of the coated sample, thus allowing direct evidence of chloride ion permeation through the polymer matrix simultaneous to water uptake to be obtained. The implications of this finding are particularly relevant towards the development of a new mechanistic model for blister initiation in coated metals.