Highly Cis-1,4 Selective Polymerization of Conjugated Dienes Catalyzed by N-heterocyclic Carbene-ligated Neodymium Complexes

Imidazolidin-2-iminato vanadium complexes for the synthesis of ethylene/propylene/5-ethylidene-2-norbornene (ENB) terpolymers with high ENB incorporation and ultra-high molecular weight

“…7,[26][27][28][29][30][31] We have reported that NHC ligands play important roles in the control of molecular weight of the resulting copolymers. 12,[32][33][34] Vanadium complexes containing NHC ligands V1-V4 (as shown in Chart 1) display quasi-living characteristics in the copolymerization of ethylene with propylene, affording ethylene-propylene copolymers with ultra-high molecular weight (M w = 1612 kg mol −1 ). 12 In order to synthesize UHMW EPDM with high ENB content, we sought to design the vanadium complexes with good catalytic activity and copolymerization ability by replacing the NHC ligands with electron-rich but less sterically hindered ligands.…”

Influence of external N‐containing donors on the neodymium‐based catalytic system for 1,3‐butadiene polymerization

“…Nd-BR has drawn particular research interest among them since it demonstrates much higher cis-1,4-selectivity (up to 99%) than other transition metal (Ti, Co, Ni) -based catalytic systems and simultaneously exhibits pseudo-living characteristic that allows well-controlling of the polymerization processes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Moreover, Nd-based polybutadienes (Nd-BR) reveals much better comprehensive mechanical properties, including higher tensile strength, lower heat buildup, and better abrasion resistance, and so forth, and therefore currently finds a wide application in high-performance automobile tires.…”

“…Today's commercially available BRs are mainly produced by anionic polymerization with lithium alkyls (Li‐BR) or by Ziegler/Natta‐technology using titanium‐, cobalt‐, nickel‐, and neodymium‐catalysts (Ti‐BR, Co‐BR, Ni‐BR, Nd‐BR), and only by the use of Ziegler/Natta‐catalysts BR grades with cis ‐1,4‐contents >93% are obtained. Nd‐BR has drawn particular research interest among them since it demonstrates much higher cis‐ 1,4‐selectivity (up to 99%) than other transition metal (Ti, Co, Ni) ‐based catalytic systems and simultaneously exhibits pseudo ‐living characteristic that allows well‐controlling of the polymerization processes 1–16 . Moreover, Nd‐based polybutadienes (Nd‐BR) reveals much better comprehensive mechanical properties, including higher tensile strength, lower heat buildup, and better abrasion resistance, and so forth, and therefore currently finds a wide application in high‐performance automobile tires.…”

PNP-Ligated Rare-Earth Metal Catalysts for Efficient Polymerization of Isoprene

“…The high stereoregularity and high molecular weight of natural rubber (NR) molecules endow the vulcanized NR material unique physical properties, such as low thermogenesis, low rolling resistance, high tear and abrasion resistance, etc. Therefore, the sPIR industry practiced various ways to mimic the NR molecular microstructure and properties [2][3][4][5][6][7]; the long-term unremitting efforts reward the rubber industry with significant physical property improvement on sPIR materials. However, in order to regulate the sPIR structure and properties matching the NR, precise control of isoprene monomer stereoregularity and connectivity in the polymer chain remain great challenges to academic and industrial researchers.…”