Synthesis of MWNTs/SiO2 supported nickel and palladium complexes and their application as catalysts for cyclic olefins polymerization

• Nickel and palladium catalysts bearing benzocyclohexan-keto(4-hydroxyethylphenyl)imine were synthesized and grafted to SiO 2 or MWNTs. • MWNTs covalently immobilized nickel catalysts exhibited high activity (3.27 × 10 4 g polymer mol Ni −1 h −1 ) and yield (98.2%) in copolymerization of norbornene and 5-norbornene-2-carboxylic ester. • The obtained copolymers exhibited good solubility, excellent thermal stability and high transparency. Nickel and palladium complexes bearing hydroxyl‑functionalized ligand {C 10 H 8 (O)C[4-C 6 H 4 (C 2 H 4 OH)NH]CH 3 } were synthesized, and supported on trimethylaluminum (Me 3 Al) activated nano-silica (SiO 2 ) or multiwalled carbon nanotubes (MWNTs). The molecular structures of the complexes have been confirmed by NMR and XPS. The effects of homogeneous nickel and palladium catalysts as well as MWNTs/SiO 2 supported nickel and palladium catalysts on the polymerization of norbornene (NB) were systematically investigated. MWNTs covalently immobilized bonded catalysts had the highest activity (3.27 × 10 4 g polymer mol Ni −1 h − 1 ) and yield (98.2%) in copolymerization for norbornene (NB) with 5-norbornene-2-carboxylic ester (NB-COOCH 3 ). The NB-COOCH 3 insertion ratio of the obtained copolymer could reach up 40.82% when the NB-COOCH 3 feed ratio was 50%. The vinyl-addition polynorbornene nanocomposites exhibited high thermal stability (T d > 400 °C) and good solubility. The SEM and TEM images of polynorbornene showed that nano-particles were dispersed uniformly in polymers. The processability and mechanical properties of the obtained copolymers were improved effectively.