Polymer-added samples, attributes

Surface characterization regarding other electron spectroscopies. To evidence specific attributes of HREELS to be compared to ESCA (XPS), UPS or AES ones, we chose to present (Figure 3) spectra recorded from polystyrenes (2). These thin film samples were made from normal and fully deuterated polymers. Immediately, it appears that HREELS is really capable of adding a new and unique dimension to electron surface analyses as ... 

After a 0.2-gm sample is added to 40 ml of hexafluoroisopropanol, the mixture is stirred overnight and filtered. A residue of approximately 2 mg remains undissolved. An IR spectrum of the vacuum-desiccated sample shows trace absorptions at 3420 and 1699cm which are attributed to entrapped starting material or endgroups on the polymer chain. An IR spectrum of the same sample although nondesiccated shows a pronounced increase in the hydroxyl absorption at 3420 cm" indicative of the hydroscopic nature of the polymer. A detailed IR (Nujol) spectrum contains the... 

Antioxidants and UV inhibitors are often added in low concentrations. Weak bands attributed to these low-molecular-weight molecules (which are essentially dissolved in the polymer) may be identified in the spectra. Under certain conditions these additives may be extractable and their unmasked spectra obtained. There also may be inorganic compounds added (in this case the additives are insoluble and are merely suspended in the polymer) to make the sample opaque or translucent, e.g., titanium dioxide, barium sulfate, and iron oxide. Other common additives include dyes and pigments. Polymer samples as you receive them, therefore, may be fairly complex mixtures, and full characterization of the sample may require extensive separation and application of other instrumental techniques. 

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