Scanning Transmission Electron Microscopy for Polymer Blends
Physical properties of the polymer can be altered by mixing one or more polymers together also known as polymer blending. The miscibility of polymers is a key parameter in determining the properties of polymer blend. Conventional transmission electron microscopy (CTEM) plays a critical role in determining the miscibility and morphology of the polymers in blend system. One of the most difficult part in polymer microscopy is the staining by heavy metals to generate contrast in CTEM. RuO4 and OsO4 are commonly used to stain the polymer materials for CTEM imaging. CTEM imaging is difficult to interpret for blends due to lack of clear distinction in contrast. Apart from having difficulty in contrast generation, staining procedures are extremely dangerous as improper handling could severely damage skin, eyes, lungs etc. We have used scanning transmission electron microscopy (STEM) to image polymer blends without any staining processes. In current work, Acrylonitrile Butadiene Styrene (ABS)/Methacrylate Butadiene Styrene (MBS) and Styrene Acrylonitrile (SAN) along with filler additive were dispersed on Polycarbonate (PC) matrix and studied by STEM/HAADF (high angle annular dark field). By using HAADF, contrast was generated through molecular density difference to differentiate components in the blend.