Investigations on homopolymerization and copolymerization of phenylacetylene and 1‐hexyne by iron‐based ziegler‐natta catalyst systems

Abstract

Homopolymerization and copolymerization of phenylacetylene (PA) and hex‐1‐yne (HX) were performed in the presence of two iron‐based catalysts having various ligands: an organic salt, iron tripropionate [Fe(prop)3] and a complex, iron triacetylacetonate [Fe(acac)3], both in combination with the triethylaluminum (AlEt3). The geometric structures of the resulting monosubstituted polyacetylene samples were investigated by 1H‐NMR, 13C‐NMR and IR spectroscopic techniques. The number‐average molecular weights were also determined. The compositions of the PA‐HX copolymers were obtained by 1H‐NMR analysis and the monomer reactivity ratios were calculated from these values using the Kelen‐Tüdös method and a nonlinear least squares curve‐fitting procedure. The proportions of cis and trans structural units in polyalkynes and the relative reactivities of two monomers PA and HX during the copolymerization were found to be strongly associated with the nature of the initiating system.