| Abstract: | Poly(dicyanoacetylene) (PDCA) has been synthesized and characterized. The pristine polymer has EPR g-value, linewidth, unpaired spin concentration, spin—spin relaxation time (T2), and room temperature dc conductivity (σRT) very similar to those of pristine cis-polyacetylene (PA), but shorter spin—lattice relaxation time (T1). Saturation doping with iodine has little effect on most EPR characteristics of the polymer except for a slight increase in T1. The doped PDCA has σRT value of only 5 X 10-9 (Ω cm)-1, indicating either low carrier concentration and/or carrier mobility. Partial cyclization of the nitrile groups by heating at 400°C of PDCA produces l-PDCA with significant increases in unpaired spin concentration and σRT but marginal effects on other properties. Saturation doping of l-PDCA with iodine increases σRT to 7 × 10-3 (Ω cm)-1 without appreciable changes in EPR characteristics. The dopants in both polymers can be removed by evacuation indicating only weak charge transfer interactions. The possible stereoelectronic contribution toward the property differences between the PDCA polymers and PA are discussed. |
