Differentiating between the diffusion of water and ions from aqueous electrolytes in organic coatings using an integrated spectro-electrochemical technique

Non‐destructive evaluations of water uptake in epoxy coating

“…This rapid water uptake may be attributed to the significant concentration gradient between the initial dry coating free film and the bulk solution, as illustrated in Figure 3b. The initial rapid increase shortly after exposing the samples to the electrolyte has been reported to be primarily due to the fast diffusion of water molecules 35 …”

“…The initial rapid increase shortly after exposing the samples to the electrolyte has been reported to be primarily due to the fast diffusion of water molecules. 35 The subsequent slower water uptake process observed during phase P2 (Figure 3a) may be attributed to water diffusion into the coating film counteracting with the initiated leaching process from the coating film, as illustrated in Figure 3b. This counteracting effect of water uptake and leaching process resulted in a slower overall increase in mass compared to phase P1.…”

FEM modelling to predict spatiotemporally resolved water uptake in organic coatings: Experimental validation by odd random phase electrochemical impedance spectroscopy measurements

“…The detailed procedure for the sample preparation specifically for ATR-FTIR in Kretschmann geometry can be found elsewhere [15]. Measurements were performed in a 1 M NaSCN aqueous solution as an infrared active pseudo-halide since technically more relevant chloride solutions are inactive in the IR region.…”

“…In-situ infrared spectra were recorded in the first 125 hours after exposure to a 1 M NaSCN solution for the PEGDA coating. The evolution of the water peak (OH-stretching vibration, 2900-3800 cm -1 ) is evaluated over time using the infrared spectrum of the dry adhesive as the reference [15]. For a more detailed interpretation, this peak was fitted according to the four different summative states of water, i.e.…”

“…18 𝛷 𝑤,𝑣 = 𝑙𝑜𝑔 𝜀 𝜀 𝑐 𝑙𝑜𝑔𝜀 𝑤 (15) The volumetric water uptake is then converted in the mass water uptake and finally recalculated into a water concentration. As such, the comparison can be carried out in terms of concentration rather than capacitance, avoiding the use of the Maxwell-Garnett approximation.…”