Development of New Imaging Modes

Two specific imaging modes developed in combining ESEM (environmental scanning electron microscopy) and STEM and developed in the MATEIS laboratory can be useful for the characterization of CNT and CNT polymer nanocomposites. 

STEM in SEM image obtained on polymer/CNT nanocomposites, experiments are in progress to characterize such sample in 3D with good resolution, contrast and important thickness of transparency, to better characterize entanglements, filler/filler interaction, etc. 

In FIB-SEM, such milling and imaging can be performed in a sequential manner thus a series of images (often called slices ) can be collected at well-defined distances. This opens up the third dimension by making a SEM combined with a FIB a well suited tool for characterizing micron and sub-micron size microstructural features in three dimensions via serial-sectioning procedures (94). 

The main drawbacks of this approach are the low availability of such instruments in laboratories, and the fact that many samples are sensitive to ion beam damage, require specific preparation (95), and can induce low contrast. Moreover, the imaging between two milling periods is typically performed in the backscattered electrons mode, which is not always favorable this is the case for carbon nanotubes in a polymer matrix as the atomic number contrast is low. This is probably the reason why, even if the FIB/SEM approach is used on polymer nanocomposites, it not used in the literature for carbon nanotubes in polymer matrix. In this last application, the tomo-STEM technique is a good alternative to obtain images of relatively thick samples with high contrast and resolution (91). 

The main goal in material science is to provide behaviour laws, i.e. to be able to predict the material properties under given conditions 

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