Direct correlation of x-ray photoelectron spectroscopy and Fourier transform infrared spectra and images from poly(vinyl chloride)/poly(methyl methacrylate) polymer blends

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Abstract
Correlative x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) studies of the complex heterogeneous structure of 50/50 poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) polymer blends are presented. The comparable lateral resolution and parallel (real-time) imaging capabilities of both techniques allow for a direct comparison of surface (XPS) and bulk (FTIR) measurements of polymer blends. To eliminate substrate influence and film-to-film differences, the same areas on the polymer films are analyzed by both methods. The effect of PMMA molecular weight on phase separation and surface segregation is evaluated using six blends with a constant PVC molecular weight and a PMMA molecular weight varying from 75 to 2132 kDa. Imaging capabilities of both methods are used for a qualitative comparison of the heterogeneous structure of the blends, while a quantitative comparison of the bulk and surface compositions of the same areas of the samples used small area spectroscopy from XPS and FTIR. Based on the small area quantitative analysis, it is concluded that surface segregation of PMMA increases with increasing molecular weight. This combination of small and large area correlative analyses in the determination of both surface and bulk properties of these heterogeneous polymer films leads to a more complete understanding of structure of complex samples.