engleski

Polymerization of diiodoacetylenes, their structure and electrical properties

Polydiiodoacetylenes (PDIA) were polymerized at different temperatures using TiCl4-AlEt3 and Ti(OBu)4-AlEt3 as catalysts. The crystallinity, concentration of unpaired spins, relaxation times, diffusion of spins, conjugations and energy gaps of the polymers were determined by X-ray diffraction, spectroscopic methods and electrical measurements. A crystalline polymer was obtained with TiCl4-AlEt3, while with Ti(OBu)4-AlEt3 an amorphous polymer was obtained. The concentration of unpaired spins for the crystalline sample was 6.7 X 10(20) and 5.3 X 10(20) Spins/mol for the amorphous one. The energy gap for the former was 0.76 and for the latter 1.29 eV, while the electrical conductivities were 5.0 X 10(-6) and 3.9 X 10(-9) OMEGA-1 cm-1 respectively. The amorphous sample had no spin saturation, a lower diffusivity of spins and a lower conjugation, as compared to the crystalline PDIA. The relaxation times were measured only for the latter and were T1 = 1.189 X 10(-5) s and T2 = 0.745 X 10(-8) s. Both samples decomposed at 300-degrees-C into iodine and charcoal. The stability of the PDIA against oxygen was much better as compared to polyacetylene.

polydiiodoacetylene ; conducting polymers ; crystallinity ; energy gaps ; concentration of unpaired spins ;

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