Simultaneous polymerization and formation of polyacetylene film on the surface of concentrated soluble Ziegler‐type catalyst solution

TLDR

The study aimed to develop a direct method for simultaneously polymerizing acetylene and forming uniformly thin polyacetylene films, examining catalyst system, concentration, and temperature. The method involved using a Ti(OC₄H₉)₄–Al(C₂H₅)₃ catalyst system at varying concentrations and temperatures to polymerize acetylene monomer directly on the catalyst solution surface. The Ti(OC₄H₉)₄–Al(C₂H₅)₃ system (Al/Ti = 3–4) at a critical Ti(OC₄H₉)₄ concentration of 3 mmol L⁻¹ produced uniform polyacetylene films; below this concentration only solids or powders formed, while the polymer’s configuration varied with temperature—yielding all‑cis chains below –78 °C and all‑trans chains above 150 °C—and electron microscopy revealed the films were composed of 200–300 Å wide fibrils of indefinite length.

Abstract

Abstract A direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC 4 H 9 ) 4 –Al(C 2 H 5 ) 3 system (Al/Ti = 3–4) and the critical concentration was 3 mmole/l. of Ti(OC 4 H 9 ) 4 . Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all‐ cis polymer was obtained at temperatures lower than −78°C, whereas an all‐ trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200–300 Å in width and of indefinite length.