Terpolymerization of Substituted Cycloolefin with Ethylene and Norbornene by Transition Metal Catalyst

Ethylene-norbornene terpolymerization experiments using 5-alkyl-substituted norbornenes (5-pentyl-2-norbornene (C(5)N) and 5-octyl-2-norbornene (C(8)N)) or dicyclopentadiene (DCPD) were conducted with two ansa-metallocenes, [Zr{(η(5)-C(9)H(6))(2)C(2)H(4)}Cl2] (1) and [Zr{(η(5)-2,5-Me(2)C(5)H(2))(2)CHEt}Cl(2)] (2), activated by methylaluminoxane (MAO). The terpolymers obtained were investigated in detail by determining the microstructure and termonomer contents by (13)C NMR, molar masses and thermal properties. Results were compared to those of ethylene (E)-norbornene (N) terpolymerizations with 1-octene. 2, with lower steric hindrance and a shorter bridge, gave the best activities, termonomer incorporation and molar masses. The size of the substituent in 5-alkyl substituted norbornene also plays a role. C(8)N gives the highest activities and molar masses, while DCPD terpolymers have the highest cycloolefin content. Terpolymers are random; their molar masses, much higher than those in 1-octene terpolymers, are in a range useful for industrial applications. Finally, T(g) values up to 152 °C were obtained. For similar N content, poly(E-ter-N-ter-C(8)N)s and poly(E-ter-N-ter-DCPD)s have the lowest and the highest T(g) values, respectively. Thus, the presence of an eight-carbon atom pendant chain in C(8)N increases the flexibility of the polymer chain more than a five-carbon atom pendant chain in C(5)N. The higher rigidity of C(5)N may lead to lower activities and to increasing probability of σ-bond metathesis and chain termination, as evidenced by chain-end group analysis.