Chemical speciation by NEXAFS spectromicroscopy: Insights from molecular modeling of polymers

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:474608

Urquhart, S G; Hitchcock, A P ^[1]; Rightor, E G ^[2]; Smith, A P; Ade, H ^[3]

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1. McMaster Univ., Hamilton, Ontario (Canada). Brockhouse Inst. for Materials Research
2. Dow Chemical USA, Freeport, TX (United States). Texas Polymer Centre
3. North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

Near Edge X-ray Absorption Fine Structure (NEXFAS) spectroscopy of polymers performed in a scanning transmission X-ray microscope (STXM) can provide chemical speciation with < 0.1 {micro}m spatial resolution in imaging mode. The core excitation spectra of molecular compounds that are structural analogues of polymers help interpret the NEXAFS spectra of polymers. The effect of {pi}-delocalization on polymer NEXAFS is discussed and illustrated by comparison to molecular spectra. Extended Hueckel calculations are particularly useful for providing insight into the relationship between chemical structure and the molecular and polymer spectra. The authors report the interpretation of experimental NEXAFS spectra of polyethylene terephthalate (PET). Molecular models indicate that NEXAFS will be sensitive to structural isomerization in polyester polymers. They demonstrate the capability of NEXAFS to distinguish hard-segment and soft-segment phase segregation in polyurethanes.

• OSTI ID: 474608
• Report Number(s): CONF-960401--; ISBN 1-55899-340-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
EXPERIMENTAL DATA
ISOMERIZATION
MOLECULAR STRUCTURE
PHASE STUDIES
POLYESTERS
POLYMERS
POLYURETHANES