Synthesis of ultra‐high‐molecular‐weight ethylene‐propylene copolymer via quasi‐living copolymerization with N‐heterocyclic carbene ligated vanadium complexes

Abstract

The quasi-living copolymerization of ethylene with propylene was achieved by using N-heterocyclic carbene (NHC) ligated vanadium complex (V3, VOCl 3 [1,3-(2,6-i Pr 2 C 6 H 3 ) 2 (NCH ) 2 C:]) due to the stabilization of active center by the introduction of bulky and electron rich NHC ligand with bulky isopropyl substituents at the ortho positions of the phenyl rings. The weight-average molecular weight (M w ) of the resulting copolymer increases linearly with its weight in 20 min. The ultra-high-molecular-weight (UHMW) ethylene-propylene copolymer (M w = 1612 kg mol −1 ) can be synthesized with V3/Et 3 Al 2 Cl 3 catalytic system. The novel complex V4 0 (VCl 3 [1,3-(2,4,6-Me 3 C 6 H 2 ) 2 (NCH ) 2 C:]Á2THF) was constructed by the introduction of two coordinated tetrahydrofuran molecules and decrease in steric hindrance at the ortho positions of phenyl rings. The UHMW ethylene-propylene copolymer (M w = 1167 kg mol −1 ) can also be synthesized by using V4 0 /Et 3 Al 2 Cl 3 catalytic system.

Copolymerization of ethylene with propylene and higher α-olefins catalyzed by (imido)vanadium(iv) dichloride complexes

“…We attribute this result to the fact that the space around the catalytic active is not so As anticipated, the obtained copolymers have a moderate propylene content (from 7.8 to 13.7 mol%). Although it is difficult to make a comparison with the literature due the different operating conditions (batch vs semibatch) and objectives, the amount of propylene incorporated in the copolymers with the vanadium complexes under investigation is comparable to the same data for vanadyl C− and N−capped tris(phenolate) complexes, 62 V(V) tetra-phenolate complexes, 63 and vanadyl calix [6]arene one, 64 but lower than N−heterocyclic carbenes, 34,65 naphthalene−bridged nitrogen−sulfonate ligands, 66 and amide V(IV) complexes. 67…”

“…EPR (CH 2 Cl 2 , 20 °C) g = 1.985, A iso ( 51 V) = 95.7 G. Anal. Calcd for C 34 atmosphere. The sample, typically 5 mg, was placed in a sealed aluminum pan, and the measurement was carried out from -80 to 130 °C (from −30 to 180 °C for PE homopolymers) using heating and cooling rate of 20 °C min −1 .…”

“…21 The recent resurgence of vanadium stems from the use of Schiff−base phenoxyimine−type ligands by Fujita at Mitsui. 13 Since then, a set of vanadium complexes supported by mono-and multi-dentate ligands, [22][23][24] including phenoxyimines, 25 aryloxides, 26 β−enaminoketonato, 27 diaminebis(phenolate), 28 bis(arylimo)acenaphthene, 29 phosphine, [30][31][32] oxazoline, 33 and N-heterocyclic carbenes 34 have been successfully developed. In this framework, we recently reported the synthesis of a set of phosphine adducts of (imido)V(IV) complexes, and we demonstrated their successful application as catalyst precursors for the copolymerization of ethylene with cyclic olefins.…”

Recent progress on NHC-stabilized early transition metal (group 3–7) complexes: Synthesis and applications

“…Zhang, Wu and co-workers reported a series of monodentate NHC-V(V) and monodentate NHC-V(III) complexes that were tested in olefin copolymerization. 66,67 Reaction of the free carbene with VOCl3 or VCl3(THF)3 led to the corresponding adducts depicted in Scheme 26.…”

Homo- and Copolymerization of Ethylene with Norbornene Catalyzed by Vanadium(III) Phosphine Complexes

“…With multiple oxidation states and coordination number and flexible geometry, applications of vanadium complexes in catalysis and polymer science continue to grow [6,7,8,9,10]. Today, vanadium catalysts are largely used for the production of elastomers [11], high-molecular-weight poly(ethylene)s (PEs) with narrow molecular weight distribution [12,13], syndiotactic poly(propylene)s [14,15], and ethylene copolymers with cyclic olefins (COCs) [16,17] and α-olefins [18,19]. Among them, there is an increased interest in COCs because of the easy availability of the monomers and unique copolymer properties.…”