NEXAFS spectromicroscopy of polymers: overview and quantitative analysis of polyurethane polymers

The successful application of X-ray spectromicroscopy to chemical analysis of polymers is reviewed and a detailed application to quantitative analysis of polyurethanes is presented. Near Edge X-ray Absorption Fine Structure ( NEXAFS) spectroscopy is the basis of chemical sensitive X-ray imaging, as w ell as qualitative and quantitative micro-spectroscopy. These capabilities are demonstrated by a review of recent work, and by presentation of new res ults outlining a methodology for quantitative speciation of polyurethane po lymers. C Is inner-shell excitation spectra of a series of molecular and po lymeric model compounds, recorded by gas phase inelastic electron scatterin g (ISEELS) and solid phase NEXAFS techniques, are used to understand the sp ectroscopic basis for chemical analysis of polyurethanes. These model speci es contain the aromatic urea, aromatic urethane (carbamate) and aliphatic e ther functionalities that are the main constituents of polyurethane polymer s. Ab initio calculations of several of the model molecular compounds are u sed to support spectral assignments and give insight into the origin and re lative intensities of characteristic spectral features. The model polymer s pectra provide reference standards for qualitative identification and quant itative analysis of polyurethane polymers. The chemical compositions of thr ee polyurethane test polymers with systematic variation in urea/urethane co ntent are measured using the spectra of model toluene diisocyanate (TDI) ur ea, TDI-carbamate, and poly(propylene oxide) polymers as reference standard s. (C) 1999 Elsevier Science B.V. All rights reserved.