Monitoring the grafting of epoxidized natural rubber by size-exclusion chromatography coupled to FTIR spectroscopy

The evaluation of heterogeneous polymeric species by a selective, dual detector size‐exclusion chromatography setup can provide accurate results on the incorporation of specific functional groups in copolymers as a function of the molar mass distribution. However, when non‐UV‐absorbing species are used in copolymerization reactions, the dual detector method becomes less reliable. By interfacing a Fourier transform infrared (FTIR) spectrometer with size‐exclusion chromatography (SEC), the problem can be overcome, making it possible to map non‐UV‐absorbing species as a function of the molar mass distribution. Coupling takes place via a solvent‐evaporation stage, which delivers the mobile phase as a dry, solvent‐free polymeric film onto a germanium disk. In this article, styrene and methyl methacrylate were grafted onto epoxidized natural rubber (ENR50) and analyzed by SEC. The accuracy of FTIR as a suitable detector was evaluated by comparing results from a dual detector SEC setup and FTIR coupled to SEC. FTIR proved to be a successful detector for the analysis of non‐UV‐absorbing species. This was consequently followed by the characterization of methyl methacrylate‐grafted ENR50. From the relevant data, Gram–Schmidt and contour plots could be made to indicate the incorporation of methyl methacrylate into the grafted epoxidized natural rubber as a function of the molar mass distribution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2539–2549, 2003