Precursor route to ethenyl-substituted polyacetylenes: synthesis of homopolymers of o-trimethylsilyl-ethers of 1-alkyl and 1-aryl substituted but-3-yn-1-ols. Desilylation, dehydration and pyrolysis to conducting films

Abstract

Poly( o-trimethylsilyl-but-3-yn-1-ols) were from trimethylsilyl ethers of RCH(OH)CH 2CCH (R=H, Me, C 6H 5 or CH=CHCH 3) via Ziegler-Natta polymerization (Fe(acac) 3/AlEt 3 in toluene, 20–35 °C) of the terminal triple bond. The polymers were obtained as yellow amorphous solids (10–23%, polymer with R=H was a viscous gum) with atactic microstructure ( 13C NMR), soluble in apolar solvents. The polymer from the monomer with R=CH=CHCH 3 could be desilylated quantitatively with potassium fluoride. Elimination of water at 200–250 °C from films of this deprotected polymer gave a semiconducting material (10 −4 S/cm) after activation with iodine. Heating the undoped film for 10–20 min at 650 °C in nitrogen atmosphere gave an intrinsically conducting brittle film (10 −2 S/cm with silvery-black lustre. Activation with iodine enhanced the conductivity to 10 1−10 2 S/cm. High conductivity was not persistent in ambient atmosphere.