Synthesis and structural characterization of ethylene–norbornene copolymer with high norbornene content catalyzed by β-diketiminato nickel/methylaluminoxane
(1964-1969) European Polymer Journal 47  #10 (2011)
Li et al of Xi’an Technological University and Sun Yat-sen (Zhongshan) University, China, copolymerized ethylene–norbornene (E–N) by using β-diketiminato nickel complexes CH{C(CF3)NAr}2NiBr (Ar = 2,6-iPr2C6H3, 1; Ar = 2,6-Me2C6H3, 2) in the presence of methylaluminoxane (MAO).  Complex 1 bearing bulky isopropyl ortho substituents showed higher activity than 2 for the E–N copolymerization. The activity of the catalytic systems increased with increasing the feed ratio of norbornene/ethylene (N/E), and gave the E–N copolymers with high norbornene content more than 75 mol%. In the microstructures of copolymers generated with the catalytic systems, norbornene microblocks with a length of two or three norbornene units have been detected.  (RDC 9/20/2011)