X-ray Photoelectron Spectroscopy of Iodine-Doped Nonconjugated Polymers

The effects of iodine doping on poly(cis-butadiene) and the cis and trans isomers of polyisoprene were examined by core-level X-ray photoelectron spectroscopy (XPS). The XPS results for iodine-doped poly(cis-butadiene) are similar to that for polyisoprene, suggesting that both polymers are doped by a similar mechanism. Core-level XPS of the iodine-doped polymers suggests that the direction of charge transfer is from the backbone carbon to the iodine species. The binding energies of the iodine species in the I3d spectra of the doped polymers indicate the presence of molecular iodine and I3− (and/or I5−) species and the absence of a significant concentration of cationic iodonium-π complex. In conjunction with conductivity measurements, XPS analysis of cryogenically cooled (−80 °C) iodine-doped poly(cis-isoprene) and poly(transisoprene) provides direct spectroscopic evidence that the conductivity of the doped polymers is due to excess iodine, present in the form of polyiodide chains. © 1993, American Chemical Society. All rights reserved.

Duke Scholars

Author Ashutosh Chilkoti Biomedical Engineering