High-Pressure Behavior of C2I2 and Polymerization to a Conductive Polymer
- Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Material Sciences and Engineering
- Carnegie Inst. of Washington, Argonne, IL (United States). Geophysical Lab., High Pressure Collaborative Access Team (HPCAT)
Crystalline diiodoacetylene (C2I2) was synthesized and then examined under high-pressure conditions using synchrotron X-ray diffraction, Raman/infrared spectroscopies, and first-principles calculations. At ~0.3 GPa, the starting tetragonal (P$$_{4_{2}}$$/n) phase, which is stabilized by donor-acceptor interactions, changes into a new orthorhombic structure (Cmca) that is more densely packed and analogous to the low-temperature phase of acetylene. Above approximately 4 GPa, compressed C2I2 molecules in the Cmca structure begin to polymerize to form a predominantly sp2 amorphous carbon network that maintains a significant fraction of C-I bonds. Transport measurements demonstrate that the polymeric material is electrically conducting. The magnitude of the electrical conductivity is similar to Br-doped polyacetylene and undoped trans-polyacetylene at 8 GPa and 1 atm, respectively. Elemental analyses performed on recovered samples show that the iodine concentration varies with specific processing conditions. Optimization of the pressure-induced polymerization pathway could allow for enhanced electrical properties to be realized, in addition to postpolymerization functionalization using the weak C-I bonds.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division; U.S. Army Research Office (ARO); Defense Advanced Research Projects Agency (DARPA); National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-06CH11357; EAR-1634415; FG02-94ER14466
- OSTI ID:
- 1558105
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 123, Issue 18; ISSN 1932-7447
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
From Molecules to Carbon Materials—High Pressure Induced Polymerization and Bonding Mechanisms of Unsaturated Compounds
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journal | September 2019 |
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