Crystalline 1,3-pentadiene polymers with syndiotactic cis-1,4 structure

摘要

Linear polypentadienes having a content of cis-1,4 units above 65%, a syndiotactic disposition of the configurations of tertiary carbon atoms and a crystalline structure in the solid state with an identity period of about 8.5 along the chain axis are made by polymerizing trans-1,3-pentadiene in the presence of a catalyst obtained by reacting a soluble cobalt compound or complex with an alkyl aluminium dichloride complexed with an organic electron-donor substance of the Lewis base type. A mixture of cis- and trans-pentadiene may replace the trans-pentadiene, but only the latter is polymerized and the cis-compound may function as the solvent for the reaction. The polymerization may also be effected in a hydrocarbon diluent. The polymer may be purified and the cis-fraction increased by solvent extraction techniques. Catalyst systems exemplified are Al(C2H5)Cl2 +thiophene+nickel or cobalt diacetylacetonate, Al(C2H5)Cl2+pyridine+nickel or cobalt diacetylacetonate, Al2(C2H5)Cl2 + thiophene nickel or cobalt stearate. The nickel compound may also be N1Cl2-pyridine complex, NCl2-triphenylphosphine, or N1Cl2-triphenyl stibine. The polymer may be vulcanized.