Imaging study heavy metal stain

For PEMs, transmission electron microscopy (TEM) was usually used to study the microstructure of PEMs according to the contrast between domains. For most PEMs, there are at least two different domains hydrophilic and hydrophobic domains. To improve the contrast between the two domains, heavy metal salt like ruthenium tetroxide and lead acetate was often used to stain the membrane [43,46]. In TEM images, the bright portions are attributed to the hydrophobic domain, while the darker portions represent the hydrophilic domain. Choi and Jo have conducted TEM tests for sulfonated PS-b-PMMA membranes with different degrees of sulfonation and blend ratios [46]. They have found that the hydrophilic domains become larger as the degree of sulfonation is increased and the morphology of the membranes... 

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