Monitoring initial contact of UV-cured organic coatings with aqueous solutions using odd random phase multisine electrochemical impedance spectroscopy

•The ORP-EIS response of organic coatings is measured shortly after immersion.•The non-stationarities found in the impedance spectra are resolved over time.•The time-resolved spectra are fitted with a physically meaningful equivalent circuit.•The fitting results show that the coatings are prone to rapid water and ion uptake.•The fitting results are verified via gravimetry and DSC measurements. In this work, a new methodology is developed to study the initial behaviour of model organic coatings shortly after coming into contact with an aqueous solution, using odd random phase electrochemical impedance spectroscopy (ORP-EIS). The impedance results are resolved over time via the calculation of the instantaneous impedance and fitted with a physically meaningful equivalent circuit. Many physical parameters could be obtained, such as the rapid water uptake, the resistivity of the coatings and the penetration depth of ions in the coatings. The fitting results were verified using differential scanning calorimetry (DSC) and gravimetry.