Homo-and copolymerization of 1-hexene and 1, 5-hexadiene by zirconocene catalysts

Abstract

In this work, homo-and copolymerizations of 1-hexene, 1,5-hexadiene were performed using zirconocene catalysts: rac-Et[Ind][subscript 2]ZrCl[subscript 2](Cat 1) and Cp[subscript 2]ZrCl[subscript 2](Cat 2) methylaluminoxane (MAO) and boron compound ([Ph[subscript 3]C][B(C[subscript 6]F[subscript 5])[subscript 4]]) as cocatalyst, the influences of catalyst amount, Al/Zr mole ratio and polymerization temperature on the catalytic activity were evaluated. The optimum condition for 1-hexene polymerization was at 60 ํC, 24 hrs, 2.5 micromol catalyst and Al/Zr mole ratio of 4000. At the same condition, Cat 1 gave comparable activity to Cat 2. For 1,5-hexadiene polymerization, the optimum condition for Cat 1 was at 30 ํC, 5 hrs, 2.5 micromol catalyst and Al/Zr mole ratio of 4000. At the same condition, Cat 1 gave higher activity than Cat 2. Comparing different cocatalyst, the activities for Cat 1/MAO were higher than Cat 1/[Ph[subscript 3]C][B(C[subscript 6]F[subscript 5])[subscript 4]] system. Furthermore, the optimum condition for 1-hexene and 1,5-hexadiene copolymerization was found at 30 ํC, 5 hrs, 50 %mol 1,5-hexadiene, 2.5 micromol catalyst and Al/Zr mole ratio of 4000. All the resulting polymers were structurally analyzed by FT-IR and [superscript 13]C-NMR spectroscopies. Glass transition temperature was determined by DSC and the molecular weights were measured with GPC. For the homopolymerization, the polyhexene prepared with Cat 1 was isotactic while with Cat 2, it was atactic. The product obtained from the polymerization of 1,5-hexadiene was cyclopolymerization of the diene, exist in both trans-isotactic and cis-atactic. For the copolymerization, it was found incorporation of both monomers in the copolymer backbone, the ratio depended on the monomer ratios.