Then the aqueous solution is removed and the RTHIL is used as the electrolyte, resulting in removal of water from the coating and subsequent decrease in water from the coating and subsequent decrease in water concentration with corresponding decreases in capacitance.
This was due, in part, to the system not fully drying under RTHIL and not fully saturating under water solution at shorter times.
The precision and accuracy is greatest for the longer cycle times, when better estimates of the saturation capacitance can be made for wetting 1/2 cycles, or dry capacitance for RTHIL 1/2 cycles.
The water volume fraction is plotted for single frequency measurements in which water (black) is used as the electrolyte since water is entering the cured epoxy resin, and when the hydrophilic RTHIL (gray) exposure results in net flux of water out of the coatings.
The use of RTHIL allows the calculation of the relative dielectric for the dry cured epoxy resin.
The ability to measure the resistance, and EIS spectra, of the dry coating is possible only by the use of the RTHIL. The decrease in resistance with time when ionic liquids are used as the electrolyte confirms that pores are being produced, perhaps by hydrodynamic stresses from water uptake concurrent with relaxation due to plasticization.
The Bode plot also shows that the cured epoxy resin gains a resistive component even using RTHIL as the electrolyte.
The resistance of the water-saturated polymer (back squares) is lower than the resistance measured with RTHIL. The resistance (R) can be converted to the materials property, resistivity (rho), for the simple geometry of a plannar coating by equation (4)