Osmium Tetroxide (OsO4)
PB-PBA Latex
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A: Latex dried at room temperature and shadowed. Note the shadows are very short or nonexistent. This is due to the fact that the latex particles are very soft and collapsed.B: After the latex was treated with OsO4 the PB was stained and "hardened". OsO4 does not stain or harden PBA. Noticethe different lengths of shadows. #1 particle has a very short
shadow indicating very little PB. Particle #3 has a long shadow indicating a large percentage of the particle is PB.
Ruthenium Tetroxide (RuO4)
Composite Core/Shell Latexes
Double Staining by OsO4 and RuO4
PB-PBA Core/PMMA Shell Latex
OsO4 stained the PB phase, RuO4 the PBA phase. The PMMA did not stain. Note the incomplete coverage of the core by the shell. The background has been negatively stained with PTA.
Negative Staining
A Composite Core/Shell Latex