Current progress in synthesis of polyacetylene films

We present current progress in syntheses of polyacetylene films. (I) We found that the catalytic system of tetra-tert-butoxytitanium [Ti(O-tert-Bu)4] and triethylaluminum [Et3Al], when prepared even with room-temperature aging but not high-temperature aging, can produce highly stretchable and highly conducting polyacetylene films with electrical conductivities of 3.0 ~ 5.5 × 104 Scm−1 after iodine doping. The ESR spectrum of the catalyst showed a single peak with hyperfine structure assignable to a binuclear complex between Ti3+ and Al species. This strongly supports the formation of homogeneous catalyst. It follows that Ti(O-tert-Bu)4 could be an alternative catalyst instead of Ti(O-n-Bu)4. (II) We synthesized two kinds of chiral titanium complexes with chiroptical 1,1ʹ-bi-2-naphthols [(R)-BINOL] as coordination ligands, abbreviated as Ti[(R)-BINOL]2 and Ti[(R)-BINOL][O-i-Pr]2,. Polymerization of acetylene using these titanium complexes with Et3Al gave free-standing films with a maximum electrical conductivity of 1.4 × 104 Scm−1 upon iodine doping after mechanical stretching. It is anticipated that the titanium complexes with both chiroptical and catalytic activities might be promising for asymmetric polymerization.