EPR spectroscopic studies of radical cations in a novel nonconjugated conductive polymer, poly(β-pinene)

Abstract

Electrical conductivity, FTIR spectroscopy and electro-optic effect in a novel nonconjugated conductive polymer, poly(β-pinene), have been recently reported. The conductivity increases by more than ten orders of magnitude upon doping with iodine. The double bonds decrease upon doping due to charge-transfer and formation of radical cations. In this report, electron paramagnetic resonance (EPR) spectroscopic measurements of poly(β-pinene) before and after iodine doping are discussed. The results show that the EPR signal increases in proportion to the doping level consistent with the formation of radical cations upon doping. Hyperfine splitting has been observed at high doping levels due to reduction in distance between the radical cation and the iodine anion. Such splitting was not observed for a doped conjugated polymer since in that case the radical is delocalized.