Polymerization of 2,4-hexadiene with neodymium catalysts and characterization of the resulting polymers

The polymerization of (E,E)-2,4-hexadiene with the Al(C₂H₅)₂Cl/Nd(OCOR)₃/Al(iBu)₃ system was examined. High molecular weight crystalline polymers were obtained in polymerizations carried out at room temperature or below. IR and NMR examination showed the polymers to consist predominantly of trans-1,4 units. Degradative oxidation gave the racemic form of 2,3-dimethylsuccinic acid, thus indicating a threo structure for the polymers. X-ray analysis indicated that the polymers contain stereoregular sequences with a trans-1,4-threo-diisotactic structure.