NMR Characterization of Carbazole-Substituted Norbornene Comonomer 9-(Bicyclo[2.2.1.]hept-5-en-2-ylmethyl)-9H-carbazole (BHMCZ) and Poly(ethylene-co-BHMCZ) Copolymer

Carbazole-substituted norbornene comonomer 9-(bicyclo[2.2.1.]hept-5-en-2-ylmethyl)-9H-carbazole (BHMCZ) can be copolymerized with ethylene using the [Ph2C(Ind)(Cp)ZrCl2] catalyst and methylaluminoxane (MAO) cocatalyst system. The microstructures of BHMCZ comonomer and of ethylene–BHMCZ copolymer containing 4.6 mol-% BHMCZ units in the chain were characterized by one-dimensional 13C DEPT and two-dimensional homonuclear 1H-1H COSY and heteronuclear 1H-13C HXCO NMR spectroscopy. The BHMCZ comonomer appears as endo and exo stereoisomers, which were identified on the basis of chemical shifts, signal multiplicities, and coupling in the 2D NMR spectra. The NMR information on the BHMCZ isomers was used to assist in the determination of the chemical shifts and microstructure of ethylene–BHMCZ copolymer. The NMR analysis of ethylene–BHMCZ copolymer indicated that exo-BHMCZ polymerizes with ethylene slightly more readily than does endo-BHMCZ under the polymerization conditions employed. Isolated segments of exo(2)-exo(5)-exo(6) and endo(2)-exo(5)-exo(6) ethylene-BHMCZ copolymer showing carbon atom numbering.