Copolymerization of 1,3-butadiene and norbornene catalyzed by Ni complexes [1]

Norbornene Copolymerization with Polar Monomers Catalyzed by Palladium Catalysts Containing Imidazolidin-2-imine/Guanidine Ligands

The development of a palladium catalyst that has enhanced catalytic performance, such as low aluminum cocatalyst loading, good copolymerization ability, high molecular weight, and excellent solubility of the (co)polymers, is still a challenge in norbornene copolymerizations. Here, a series of PdCl2 and PdMeCl complexes containing differently substituted anilines and imidazolidin-2-imine/guanidine ligands was successfully synthesized and characterized. X-ray diffraction analysis results revealed that these Pd complexes adopted an almost square-planar geometry, and the six-membered chelate ring showed structural distinctions as compared to traditional N^N-based α-diimine and β-diimine Pd complexes. These Pd complexes were activated by EtAlCl2 and then exhibited moderate activity (104-105 g mol-1 h-1) and good thermal stability (up to 90 °C) for norbornene polymerization to produce high-molecular-weight PNBs (Mn up to 96.4 kg mol-1) with narrow polydispersities (PDI as low as 1.39). These Pd complexes also exhibited good polar group tolerance in the copolymerization of norbornene with methyl 5-norbornene-2-carboxylate and methyl 10-undecenoate, in which the activity was achieved up to 7.04 × 104 g mol-1 h-1. It furnished polar functionalized norbornene-based copolymers with high molecular weight (Mn up to 63.1 kg mol-1), narrow PDI, reasonable polar monomer incorporation, and good solubility. These Pd catalysts exhibited an enhanced copolymerization ability to produce PNB or NB-based copolymers, representing significant progress in this field.

Homo- and copolymerization of norbornene using tridentate IzQO palladium catalysts with dimethylaminoethyl as a side arm

Rigid IzQO–Pd catalysts were synthesized by Rh(iii)-catalyzed C–H/alkyne annulation and applied for the homo- and copolymerizations of norbornene with polar vinyl monomers.

Effect of the number of arms on the mechanical properties of a star-shaped cyclic olefin copolymer

The increase of aggregation number in a star-shaped cyclic olefin copolymer was succeeded by using a triazine-based secondary amine, which caused a drastic change in physical properties without changing the thermal properties.