J. G. Rodríguez, A. Lafuente and R. Martín-Villamil
Polymerization of phenylacetylene was carried out with the microheterogeneous Ti(OR)4AlEt3 and homogeneous V(acac)3AlEt3 Ziegler-Natta catalyst system. Influence of some co-catalyst such as pyridine and phenylacetylide, solvent, temperature, and time parameters, have been analyzed. Both catalyst systems produced poly(phenylacetylene) (PPA) and a 1,2,4-/1,3,5-triphenylbenzene (TPB) cyclotrimers mixture in variable molar ratio. The titanium catalyst showed the lowest PPA/TPB ratio. The 1,2,4-/1,3,5-TPB molar ratio decreased with increasing PPA. On the basis of the spectroscopic data, PPA had a cis-transoidal stereo-regular structure. The molecular mass of PPA was determined by vapor pressure osmometry and by GPC chromatography methods. A mechanism for the polymerization reaction versus cyclotrimerization was proposed.