Substrate protection is a paramount requirement of efficient coatings performance, andto provide adequate corrosion protection coatings must prevent, or at least limit, the passageand accumulation of corrosive species (including water, oxygen, and electrolytes) through tothe metal. Due to its abundance, high surface energy, and small molecular size, water is anaggressive penetrant and plays a central role in degrading coatings in addition to reducing orlowering thermal and mechanical properties of the polymeric binder component throughhydroplasticization. As most coatings systems include multiple layers which typically consist ofvarying polymer chemistry and solvent/pigment compositions, it is possible that interfacialregions between coating layers will develop and establish influence over transport propertiesand thereby corrosion protection. This investigation sought to understand the role of specificpolymer building blocks or coating characteristics (including Tg, stoichiometry, solids loading,and cure) in the development of polymer-polymer interfaces and the resulting corrosionprotection in multi-layer coatings systems. Bilayer films were produced, and the interfacialregions were characterized via atomic force microscopy (AFM), scanning electron microscopy(SEM), and nano-indentation before evaluating the impact of these interfaces on watertransport using dynamic vapor sorption (DVS) and permeation cup methods. These results arecompared with water transport properties of fully formulated coatings to make predictions ofcorrosion protection differences derived from interfacial properties.
展开▼
