Chemical Mapping of Rubbers and Polymers via Confocal Raman Spectroscopic Imaging

Abstract

Abstract Confocal Raman Spectroscopic Imaging has been demonstrated as a non-destructive technique to determine the spatial and chemical content of rubbers and polymers. Raman spectroscopy is a particularly useful tool for characterizing chemicals and mixtures because each chemically-distinct species has a unique Raman spectrum. The addition of confocal optics to the microscope greatly improves both the lateral and axial spatial resolution of the instrument. The lateral resolution of the instrument is less than one-third of a micron. The axial resolution, the resolution in the direction of incident light propagation, is as good as two microns with an air objective and on the order of a micron for an oil immersion objective. The vast enhancement of resolution provided by the confocal optical arrangement allows rubber and polymer mixtures to be mapped in multiple dimensions with excellent spatial, chemical, and morphological specificity. Confocal Raman microscopy is a rapid technique that should be considered as an alternative, or in addition, to analysis that requires other microscopic techniques such as atomic force microscopy (AFM) or scanning electron microscopy (SEM).