Deuterium isotope effects in polymerization of benzene under pressure
- Univ. of Utah, Salt Lake City, UT (United States)
- Northwestern Univ., Evanston, IL (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Carnegie Institute of Washington, Argonne, IL (United States)
The enormous versatility in the properties of carbon materials depends on the content of the sp2 and sp3 covalent bonds. Under compression, if intermolecular distances cross a critical threshold, then unsaturated hydrocarbons gradually transform to saturated carbon polymers. However, the mechanism of polymerization, even for benzene, the simplest aromatic hydrocarbon, is still not understood. We used high-pressure synchrotron X-ray, neutron diffraction, and micro-Raman spectroscopy together with density functional calculations to investigate the isotope effects in benzene isotopologues C6H6 and C6D6 up to 46.0 GPa. Raman spectra of polymeric products recovered from comparable pressures show the progression of polymerization exhibiting a pronounced kinetic isotope effect. Kinetically retarded reactions in C6D6 shed light on the mechanism of polymerization of benzene. Lastly, we find that C6D6-derived products recovered from P < 35 GPa actively react with moisture, forming polymers with higher sp3 hydrogen contents. Significant isotopic shift (≥7 GPa) in persistence of Bragg reflections of C6D6 is observed.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1366413
- Journal Information:
- Journal of Physical Chemistry Letters, Vol. 8, Issue 8; ISSN 1948-7185
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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