POLYMERIZATION OF 1,3-PENTADIENE BY COBALT CATALYSTS SYNTHESIS OF 1,2 AND CIS-1,4 SYNDIOTACTIC POLYPENTASIENES

A report is given on the polymerization of 1,3-pentadiene by cobalt catalysts prepared from AlEt2Cl, Al2Et3Cl3 or alkyl aluminum compounds containing AlOAl bonds. Depending on the aluminum compound used for preparing the catalyst and on the polymerization solvent (benzene, n-heptane, cis-2-butene), different polymers are obtained, i.e., crystalline polymers with a cis-1,4 syndiotactic structure, amorphous polymers composed of cis-1,4 and 1,2 units, and weakly crystalline polymers with a 1,2 syndiotactic structure. Characterization of the polymers is reported. The results are discussed in the light of the current theories on the mechanism of catalysis of stereospecific polymerization. © 1969.