RESUMO
Secondary ion mass spectrometry (SIMS) is used to probe the movement of macromolecules in heterogeneous organic systems. Using 13C tracer labeling and two model systems, polystyrene/poly(2-vinylpyridine) (PS/P2VP) and polystyrene/poly(4-bromostyrene) (PS/P4BrS), the diffusion of 13C-labeled PS has been investigated near the respective heterogeneous interfaces using a CAMECA-IMS-6F magnetic sector mass spectrometer. 13C labeling has been shown to greatly minimize matrix effects (i.e., changes in secondary ion yields due to changing chemical environment) in heterogeneous systems. P2VP is a nitrogen-rich polymer (C7H7N monomer composition), making it an excellent model polymer for exploration of this technique for potential future use in biological applications, and probing the PS/P4BrS interface demonstrates the versatility of this technique for analysis of various heteroatom-containing materials. Results confirm that the 13C-labeling method does indeed allow for quantitative analysis of molecular movement in heterogeneous organic systems containing matrix-enhancing heteroatoms such as nitrogen. Therefore, extension of this method to more complicated biological systems involving multiple heteroatoms (oxygen, nitrogen, etc.), layers, and heterogeneous interfaces, as well as two- and three-dimensional profiling and imaging using SIMS, can be envisaged.
RESUMO
Deuterium labeling has been shown previously to affect thermodynamic interactions at polymer surfaces, polymer/polymer heterogeneous interfaces, and in bulk (away from a surface or interface). However, the changes in polymer-polymer interactions due to deuterium labeling have not been thoroughly investigated for highly immiscible systems. It is shown here that deuterium labeling can influence polymer-polymer interactions at heterogeneous interfaces with highly immiscible systems, namely, polystyrene/poly(2-vinylpyridine) (PS/P2VP), polystyrene/poly(4-vinylpyridine) (PS/P4VP), and polystyrene/poly(methyl methacrylate) (PS/PMMA). Using secondary ion mass spectrometry, segregation of deuterium labeled polystyrene (dPS) in a dPS + unlabeled PS (dPS:hPS) blend layer was observed at the dPS:hPS/hP2VP, dPS:hPS/hP4VP, and dPS:hPS/hPMMA heterogeneous interfaces. However, a reference system involving PS on a PS brush shows no segregation of dPS to the interface.