Semicrystalline polymers OsO4 staining

Polymers containing unsaturated rubber and semicrystalline polymers are often effectively stained using osmium tetroxide. What about materials that do not show such differential staining Two examples will be described where reactive (unsaturated) materials are included into the polymer to provide reaction sites. Inclusion of a stainable unsaturated polymer was shown for cellulosics [81] and synthetic fibers [106]. The initial work was focused on improvement of properties of cellulosics by inclusion of an elastomer between the microfibrils. OSO4 staining... 

Preferential absorption of OSO4 has been shown [115] to reveal spherulites in semicrystalline PET. Stefan and Williams [116] work on ABS-poly-carbonate blends also showed contrast by selective absorption. The dark SAN polymer, in this latter study, contains the osmium stained rubber particles while the polycarbonate was not stained. Niimoni et al. [117] found that there is often enough phase contrast in stained copolymers which have different degrees of unsaturation or functional groups like -OH, -0-, or as they each vary in reactivity with the stain. A specially constructed pressure bomb was developed by Edwards and Phillips [118] in order to terminate crystallization and fix polymers with OSO4 at elevated pressure. This method has permitted determination of lamellar growth rates and the observation of developments in crystalline morphology. 

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