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 (C5N) and 5-octyl-2-norbornene (C8N)) or dicyclopentadiene (DCPD) were conducted with two ansa-metallocenes, [Zr{(eta(5)-C9H6)(2)C2H4}Cl2] (1) and [Zr{(eta(5)-2,5-Me2C5H2)(2)CHEt}Cl-2] (2), activated by methylaluminoxane (MAO). The terpolymers obtained were investigated in detail by determining the microstructure and termonomer contents by C-13 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. C8N 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 degrees C were obtained. For similar N content, poly(E-ter-N-ter-C8N)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 C8N increases the flexibility of the polymer chain more than a five-carbon atom pendant chain in C5N. The higher rigidity of C5N may lead to lower activities and to increasing probability of sigma-bond metathesis and chain termination, as evidenced by chain-end group analysis.