Fig. 4 Dependence of the EZ width on the ethanol concentration. Mean and SD values are plotted (n = 3–5 different Nafion samples)(3–5) to (10–12) % results in an increase of the EZ size, while higher concentrations of ethanol diminish the size. Meanwhile, the EZ size reduction at higher ethanol concen- trations shows a more complex curve. To some extent the results appear similar to those of an earlier investigation [4], where the EZ width in 100% ethanol was equal to 38 lm, close to the value of 45 lm reported here for the highest ethanol concentration, 95%.