Mass spectrometry intractable polymers

The instrumental aspects and applications of stress mass spectrometry (stress MS) to polymeric materials is reviewed critically from the inception of the technique to the present. Stress MS experiments are performed by mechanically deforming polymeric materials directly in the ion source housing of a time-of-flight mass spectrometer and mass analyzing the evolved volatile compounds. This technique has been applied to the study of stress-induced chemical reactions in polymeric materials, i.e., mechanochemistry, and to the characterization of residual volatile compounds in intractable polymer and composite matrices. Several polymeric systems ranging from polystyrene to fiber-epoxy composites have been studied by this technique. The significance of results achieved to date is assessed, and a systematic framework for further studies is developed. 

The THM reaction linked to GC, GC/mass spectrometry (MS), and MS has been successfully applied to the chemical characterization of a number of synthetic and natural products, including resins, lipids, waxes, wood products, soil sediments, and microorganisms. This technique is also very effective for the detailed characterization of the synthetic polymeric materials, especially the condensation polymers, such as polyesters and polycarbonates, because many simplified pyrograms are usually obtained that consist of peaks of methyl derivatives from the constituents of the polymer samples almost quantitatively. In this chapter, the instrumental and methodological aspects of Py-GC in the presence of the organic alkali are briefly described, and then some typical applications to the precise compositional analyses and microstructural elucidation inclusive of the intractable cross-linking structures for various condensation type polymeric materials are discussed. 

A few MS techniques have been available for the analysis of intractable polymers for a number of years. The most significant of these are laser desorption/ionization (LDI) (45) and secondary ion mass spectrometry (46). The major drawback with these techniques is the low production of intact molecular ions for the oligomers, especially with increasing molar mass. Another approach has been to use chemical modifications in order to make the polymer soluble in a particular solvent so that MS analysis can be conducted. However, these modifications are both time consuming and alter the original molecular structure of the polymer of interest. 

Pyrolysis - gas chromatography has been used for many years for the characterisation of plastics materials, particularly when they are of an intractable nature owing to cross-linking or are very heavily filled. The technique has now been extended to include mass spectrometry and is of particular value when minor components need to be identified. An example has been described by Sharp and Paterson for the identification of small amounts (1-10%) of copolymerised imsaturated acids in acrylic polymers. The method can be summarised as follows ... 

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