SIZE-EXCLUSION CHROMATOGRAPHY FOURIER-TRANSFORM IR SPECTROMETRY USING A SOLVENT-EVAPORATIVE INTERFACE

A solvent-evaporative interface is used to deposit each fraction obtained from size-exclusion chromatography (SEC) as a dry polymer film on an IR transparent disc for subsequent IR analysis. Spectra without solvent interference bands result. However, in addition to removing the solvent, the interface must provide polymer films that yield undistorted spectra. Christiansen distortion is particularly troublesome because it interferes with quantitative interpretation In the affected spectrum. Undistorted spectra were invariably obtained from continuous films and sometimes obtained from discontinuous films (separate particles). Carbon-coated KCl discs and either bare or carbon-coated germanium discs provided morphologies with good spectra. Polymer deposition on bare KCI discs often provided unacceptable morphologies. Surface-wetting properties of the substrate appear to dominate deposit morphology.