Synthesis and characterization of a conducting polyfunctional polydiacetylene

Abstract

The dimer of 1,11-dodecadiyne was synthesized by controlling the kinetics of the Glaser coupling reaction. Preliminary characterization was accomplished using gel permeation chromatography and differential scanning calorimetry. Microscopic single crystals of the dimer, obtained from a hexane solution, were used for diacetylene polymerization by Co 60 γ-irradiation. The corresponding phase transition from dimer to polymerized dimer was studied by electron diffraction. The existence of an intermediate structure over a range of conversion was apparent from these studies. Macroscopic polymerized single crystals were obtained by γ-ray polymerization X-ray structure analysis was accomplished using these crystals. The unit cell was monoclinic, space group P2/ n. Nine hundred and twenty six observed data points were used for the refinement. The final residual was 0.08. The refined structure was found to be composed of parallel sheets containing alternating trans polyacetylene and polydiacetylene chains. Conductivity (10 −2 ω −1 cm −1 at room temperature) was measured as a function of temperature and the resulting activation energy was compared to the band gap calculated by assuming π electron overlap between polyacetylene and polydiacetylene chains.