In this study, the composition of an epoxy-amine matrix was varied to induce small incremental changes in the network hydrophilicity as quantified via Hansen solubility parameter. A diglycidyl ether of bisphenol-A-based epoxy resin was formulated with a commercial polyamidoamine curative at 1∶1 epoxy-amine hydrogen ratio, and 15 weight% of the reactive amine hydrogens by equivalent were substituted with a mixture of hydrophilic (Jeffamine~® ED900) and hydrophobic (Jeffamine THF100) amine-functional polyethers of similar molecular weight. By varying the ratio of ED900:THF100 (90:10, 75:25,50:50,25:75, and 10:90), the overall matrix hydrophilicity was adjusted incrementally. Our research focused on quantifying the results from these compositional changes on water uptake and transport in combination with corrosion performance. Water uptake was characterized via gravimetric immersion while network physical properties were investigated using dynamic mechanical analysis and coatings performance tests. It was found that while the networks exhibited similar dry state T_gs (～ 55°C) and glassy modulus (～ 1.2 GPa), a gradient of water uptake rates and saturation levels resulted from the varying hydrophilic/hydrophobic component ratios. Primers formulated with these matrices exhibited a range of corrosion growth behaviors as well, in systems containing either chromate-based pigment or an organic alternative, higher water uptake rates resulted in greater inhibitor solubilization and substantially lower corrosion area.
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