The effect of osmium staining on lamellar spacing in thin polystyrene-polyisoprene diblock copolymer films

Thin films of lamellar-structured polystyrene-block-polyisoprene were vapour stained with osmium tetroxide and compared using transmission imaging in an environmental scanning electron microscope to unstained films of the same polymer. Staining was found to swell the affected phase by a factor of 1.15 in-plane, compressing the unstained phase to a factor of 0.71 of its original size as it did so. Additionally, images exhibiting contrast between phases in the unstained sample were successfully taken with conventional transmission electron microscopy, showing that staining is not necessary for imaging such samples.