Combined X-ray photoelectron spectroscopy and time-of-flight secondary ion MS surface quantitative analysis of polymer blends with varying mixing thermodynamics.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to quantitatively correlate to the surface chemical composition determined from XPS in poly(styrene-co-p-hexafluorohydroxyisopropyl-alpha-methyl styrene)/poly(4-vinyl pyridine) (PS(OH)/PVPy) blends or complexes when the p-(hexafluoro-2-hydroxyisopropyl)-alpha-methylstyrene (HFMS) contents in PS(OH) copolymers were gradually increased. It was found that different mixing thermodynamics, such as immiscibility, miscibility, and complexation, have little effect on the quantitative analysis of PS(OH) copolymers in the blends or complexes using TOF-SIMS. In the positive spectra, either the normalized intensities or relative peak intensities can be used to quantitatively analyze the surface HFMS, PS(OH), or PVPy concentration when peaks at m/z = 257, 271, 285, and 373 are used for HFMS, peaks at m/z = 91, 103, 105, 115 for styrene, and peaks at m/z = 132, 195, 209 for PVPy. In the negative spectra, the normalized intensities of peaks characteristic of PVPy seem to be not affected by hydrogen bonding formation and can be used in quantitative analysis, whereas peaks characteristic of HFMS, such as a peak at m/z = 283, cannot be used in quantitative analysis due to enhancement of its secondary ion yield resulting from hydrogen bond formation.