Inner-Shell Excitation Spectroscopy of Polymer and Monomer Isomers of Dimethyl Phthalate

Urquhart, Stephen G.; Hitchcock, Adam P.; Smith, A. P.; Ade, Harald; Rightor, E. G.

doi:10.1021/jp963419d

Cited by 67 publications

(72 citation statements)

References 25 publications

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“…Further discussion of the core spectra of 1,4-DMT is presented elsewhere, in the context of a comparison of the spectra and ab initio calculations of 1,2-, 1,3-, and 1,4-dimethyl phthalate isomers and their corresponding oligimers. 58 …”

Section: Relative Capabilities Of Stem-eels Versus Stxm-xas For Analymentioning

confidence: 99%

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

et al. 1997

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The C 1s and O 1s X-ray absorption spectra of poly(ethylene terephthalate) (PET) have been recorded using transmission, fluorescence, and electron yield detection. The corresponding electron energy loss spectra (EELS) have been recorded in a scanning transmission electron microscope. These results are compared to the C 1s and O 1s spectra of gas phase 1,4-dimethyl terephthalate (the monomer of PET) recorded using EELS. The comparison of monomer and polymer materials in different phases and with different techniques has aided the understanding of the relative strengths and limitations of each technique as well as assisting the spectral interpretation. Good agreement is found in the overall shape and the energies of the spectral features. Relatively minor differences in intensities can be understood in terms of the properties of the individual spectroscopic techniques. The critical dose for radiation damage by 100 keV electrons incident on PET at 100 K is found to be (1.45 ( 0.15) × 10 3 eV nm -3 . In contrast, the critical dose for radiation damage by 302 eV X-rays incident on PET at 300 K is (1.2 ( 0.6) × 10 4 eV nm -3 . A figure of merit involving the product of critical energy dose and spectral efficiency (as expressed by the appropriate G value) is developed. This indicates that, for near-edge studies involving a 20 eV spectral width, there is ∼500-fold advantage of X-ray absorption studies on room temperature PET relative to electron energy loss studies of cooled PET.

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Section: Relative Capabilities Of Stem-eels Versus Stxm-xas For Analymentioning

confidence: 99%

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

et al. 1997

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“…11 polymers, particularly when the "spatial extent" of π* delocalization in the polymer is properly accounted for in the molecular model structure. 36,22 The effect of "σ-delocalization" and the contentious issue of Rydberg transitions 29 in the core excitation spectroscopy of polymers deserve further experimental and theoretical study. Figure 3 presents the C 1s spectra of four TDI polyurethane polymers synthesized with poly(propylene oxide) polyether polyols of different molecular weight (250, 700, 1500, and 3000 MW), together with the C 1s spectrum of poly(propylene oxide).…”

Section: Distinguishing Urea and Carbamatementioning

confidence: 99%

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

et al. 1999

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The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon 1s 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 MDIbased and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.

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“…At one end of the scale, the various contributions to can be parsed into hypothetical anisotropic monomer tensor components of , positioned and oriented according to a structural model for aPS, and tested against measured scattering. At the other end, ab initio DFT calculations of resonant scattering factors [18,[54][55][56][57][58] of carbon atoms in quantum MD models [59] could be coarse-grained at the functional group, monomer, or larger level and used to calculate scattering. This latter approach can directly explore the extent to which monomer scattering properties are identical and independent of non-bonding chain conformation effects, and to more directly explore the backbone and phenyl contributions to both spatially-averaged reflectivity and spatially-resolved scattering.…”

Section: B Depolarized Scattering From Short-range Orientation Fluctmentioning

confidence: 99%

Molecular anisotropy effects in carbonK-edge scattering: Depolarized diffuse scattering and optical anisotropy

Stone

Kortright

2014

Phys. Rev. B

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Some polymer properties, such as conductivity, are very sensitive to short-and intermediaterange orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

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Inner-Shell Excitation Spectroscopy of Polymer and Monomer Isomers of Dimethyl Phthalate

Cited by 67 publications

References 25 publications

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

Molecular anisotropy effects in carbonK-edge scattering: Depolarized diffuse scattering and optical anisotropy

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