The protective quality of a coating is often measured by how long it delays the arrival of water to the substrate. The transport of water in, redistribution within, and eventually through a coating to the substrate has long been investigated through electrochemical impedance spectroscopy (EIS). EIS measurements employing alternating nonaqueous (room temperature ionic liquids, RTIL) and aqueous electrolytes elucidated the behavior of water within the coating. Diffusion coefficients could be measured and the redistribution of water into percolating paths identified. The use of RTIL alternating with aqueous electrolytes allows determination of intrinsic properties (water volume fraction at saturation and relative dielectric) and kinetic properties predicted by the Brasher Kingsbury formulation. This article focuses on the sensitivity of these intrinsic and kinetic properties to test duration in an unique experimental method.
Bibliographical noteFunding Information:
Acknowledgment The authors would like to thank the US Air Force Office of Scientific Research, contract number FA9599-04-1-0368, and Army Research Laboratory, contract number W911NF-04-2-0029, for support of this research.
- Diffusion coefficient
- Electrochemical impedance spectroscopy
- Ionic liquids
- Water uptake