Application of Two-Dimensional Correlation Infrared Spectroscopy to the Study of Miscible Polymer Blends

In the preceding paper in this series, generalized two-dimensional (2D) correlation vibrational spectroscopy was applied to the study of immiscible polymer blends. Here miscible systems are considered. It is shown that new features that appear in 2D plots that were previously interpreted in terms of bands that can be associated with specific interactions or conformational changes are artifacts of the procedure used to obtain these plots. The features actually correspond to “lobes” or points of inflection in the difference spectra used to generate the 2D plots that are a result of small frequency shifts or bandwidth changes.