Near-edge X-ray absorption fine structure spectroscopy of MDI and TDI polyurethane polymers

The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to di fferences in key chemical components of polyurethane polymers is presented. Carbon Is NEXAFS spectra of polyurethane polymers made from 4,4'-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDI-based and TDT-based polyurethane polymers. N EXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguis hed. The NEXAFS spectroscopy of the polyether component of these polymers i s discussed, and the differences between the spectra of MDI and TDI polyure thanes synthesized with polyether polyols of different molecular compositio n and different molecular weight are presented. These polymer spectra repor ted herein provide appropriate model spectra to represent the pure componen ts for quantitative microanalysis.