Highly efficient cis-1,4 polymerisation of isoprene using simple homoleptic amido rare earth-based catalysts

Ammonium Tetrakis(pentafluorophenyl)borate: Preparation and Application in Olefin Coordination Polymerization as the Cocatalyst Compound

Metallocene catalysts have attracted much attention from academia and industry for their excellent catalytic activity in the field of olefin polymerization. Cocatalysts play a key role in metallocene catalytic systems, which can not only affect the overall catalytic activity, but also have an obvious influence on the structure and properties of the polymer. Although methylaluminoxane (MAO) is currently the most widely used cocatalyst, its price increases the production cost of polyolefin materials. Ammonium tetrakis(pentafluorophenyl)borate has shown excellent performance in polymerization, being one of the best substitutes for the traditional cocatalyst MAO. Compared with the main catalyst, whose composition and structure are relatively complex, the research on cocatalyst is very limited. This review mainly introduces the research history, preparation methods, and application progress in polymerization of ammonium tetrakis(pentafluorophenyl)borate, deepening our understanding of the role of cocatalyst in polymerization, with the hope of inspiring brand-new thinking on improving and enhancing the overall performance of catalyst systems.

Triisobutylaluminium-promoted formation of lanthanide hydrides

Discrete lanthanide(III) isobutylaluminates Ln[N(SiMe₃)₂](HAliBu₃)(AliBu₄) (Ln = La, Pr, Nd) are obtained from Ln[N(SiMe₃)₂]₃ and triisobutylaluminium (TIBA). Nd[N(SiMe₃)₂](HAliBu₃)(AliBu₄) reacts with crown ether to give the ion pair [Nd(18-c-6){N(SiMe₃)₂}(HAliBu₃)][AliBu₄], featuring a strong Nd-H interaction in the solid state. The equimolar reaction of La[N(SiMe₃)₂](HAliBu₃)(AliBu₄) with fluorene resulted in the concomitant formation of [(μ-fluorenyl)₃La₂(μ-H)(HAliBu₃)₂] and (fluorenyl)₂La[N(SiMe₃)₂]. [(μ-Fluorenyl)₃La₂(μ-H)(HAliBu₃)₂] features fluorenyl ligands with a μ-η⁶:η⁶ coordination around the hydrido-bridged dilanthanum core motif. The reported complexes are the first crystallographically characterized, ancillary ligand-free lanthanide(III) tetraisobutylaluminates, and display potential model systems for Ziegler-type polymerization catalysis.

Coordinative Chain Transfer Polymerization of Sustainable Terpene Monomers Using a Neodymium-Based Catalyst System

The present investigation involves the coordinative chain transfer polymerization (CCTP) of biobased terpenes in order to obtain sustainable polymers from myrcene (My) and farnesene (Fa), using the ternary Ziegler–Natta catalyst system comprising [NdV₃]/[Al(i-Bu)₂H]/[Me₂SiCl₂] and Al(i-Bu)₂H, which acts as cocatalyst and chain transfer agent (CTA). The polymers were produced with a yield above 85% according to the monomeric consumption at the end of the reaction, and the kinetic examination revealed that the catalyst system proceeded with a reversible chain transfer mechanism in the presence of 15–30 equiv. of CTA. The resulting polyterpenes showed narrow molecular weight distributions (M_w/M_n = 1.4–2.5) and a high percent of 1,4-cis microstructure in the presence of 1 equiv. of Me₂SiCl₂, having control of the molecular weight distribution in Ziegler–Natta catalytic systems that maintain a high generation of 1,4-cis microstructure.

Terpene Coordinative Chain Transfer Polymerization: Understanding the Process through Kinetic Modeling

The interest in the Coordinative Chain Transfer Polymerization (CCTP) of a family of naturally occurring hydrocarbon monomers, namely terpenes, for the production of high-performance rubbers is increasing year by year. In this work, the synthesis of poly(β-myrcene) via CCTP is introduced, using neodymium versatate (NdV₃), diisobutylaluminum hydrade (DIBAH) as the catalytic system and dimethyldichlorosilane (Me₂SiCl₂) as the activator. A bimodal distribution in the GPC signal reveals the presence of two populations at low conversions, attributable to dormants (arising from reversible chain transfer reactions) and dead chains (arising from termination and irreversible chain transfer reactions); a unimodal distribution is generated at medium and high conversions, corresponding to the dominant species, the dormant chains. Additionally, a mathematical kinetic model was developed based on the Method of Moments to study a set of selected experiments: ([β-myrcene]₀:[NdV₃]₀:[DIBAH]₀:[Me₂SiCl₂]₀ = 660:1:2:1, 885:1:2:1, and 533:1:2:1). In order to estimate the kinetic rate constant of the systems, a minimization of the sum of squared errors (SSE) between the model predicted values and the experimental measurements was carried out, resulting in an excellent fit. A set of the Arrhenius parameters were estimated for the ratio [β-myrcene]₀:[NdV₃]₀:[DIBAH]₀:[Me₂SiCl₂]₀ = 660:1:2:1 in a temperature range between 50 to 70 °C. While the end-group functionality (EGF) was predominantly preserved as the ratio [β-myrcene]₀:[NdV₃]₀ was decreased, higher catalytic activity was obtained with a high ratio.

Bio-elastomers based on polyocimene synthesized via coordination polymerization using neodymium-based catalytic systems

Towards the development of eco-friendly alternatives of elastomeric materials, which can replace petroleum-based materials, it is crucial to explore different monomers and catalytic systems in order to find the best possible combinations for specific applications. Herein, we report the synthesis of polyocimene via coordination polymerization using two different neodymium-based catalysts (NdV3 and Nd(Oi-Pr)3), activated by alkylaluminums/organoboron compounds. By varying the type of co-catalyst species, halide donors, and reaction parameters, we have demonstrated the possibility to obtain polymers with a controlled microstructure and tunable properties, in terms of molecular weight characteristics and kinetics. Our results provide important insights towards the search for the optimum catalytic system to produce bio-elastomers.

Synthesis of characteristic polyisoprenes using rationally designed iminopyridyl metal (Fe and Co) precatalysts: investigation of co-catalysts and steric influence on their catalytic activity

A series of iminopyridyl ligand-based iron and cobalt complexes are utilized as catalysts in isoprene polymerization, in which the microstructure of resultant polyisoprenes was investigated.

Preparation of Butadiene-Isoprene Copolymer with High Vinyl Contents by Al(OPhCH₃)(i-Bu)₂/MoO₂Cl₂∙TNPP

In this study, a butadiene-isoprene coordination polymerization was initiated by a binary molybdenum (Mo)-based catalytic system consisting of modified MoO₂Cl₂ as the primary catalyst, triethyl aluminum substituted by m-cresol as the co-catalyst and tris(nonyl phenyl) phosphate (TNPP) as the ligand. The effects of the amount of catalyst and type of co-catalyst were investigated in detail. Experimental results indicated that when the butadiene-isoprene coordination polymerization was initiated by the binary Mo-based catalytic system, the monomer conversion could reach 90%. The resulting butadiene units were primarily based on 1,2-structures, and the reactivity ratios of butadiene and isoprene were 1.13 and 0.31, respectively. The reaction in the catalytic system was attributed to the non-ideal and non-constant ratio copolymerization. When the addition of isoprene monomers was relatively low, the isoprene units on the butadiene-isoprene copolymers were primarily based on the 1,2- and 3,4-structures. Moreover, the orientation of active centers to 1,2- and 3,4-structures gradually decreased with an increase in the addition of isoprene monomers, which resulted in the generation of high vinyl butadiene-isoprene copolymers.

Bidentate forms of β-triketimines: syntheses, characterization and outstanding performance of enamine–diimine cobalt complexes in isoprene polymerization

When a normally tridentate β-triketimine ligand binds to Co(ii) in a bidentate enamine–diimine form, is partnered with the weakly co-ordinating BArF anion and activated with ethylaluminiumsesquichoride, the most active catalyst yet found forcis-1,4-selective polymerization of isoprene results.

Alpha and beta diimine cobalt complexes in isoprene polymerization: a comparative study

Isoprene was polymerized by diimine cobalt catalyst in the presence of DEAC to produce cis-1,4 and 3,4 polyisoprene.

Rare-earth metal bis(silylamide) complexes supported by mono-dentate arylamido ligand: synthesis, reactivity, and catalyst precursors in living cis-1,4-selective polymerization of isoprene

One-pot salt metathesis reaction of LnCl₃, [2,6-ⁱPr₂C₆H₃N(SiMe₃)]Li and LiN(SiHMe₂)₂ in 1 : 1 : 2 molar ratio gave [2,6-ⁱPr₂C₆H₃N(SiMe₃)]Ln[N(SiHMe₂)₂]₂(THF) (Ln = Y, Lu, La), which were highly active for cis-1,4 polymerization of isoprene in the presence of [Ph₃C][B(C₆F₅)₄] and AlⁱBu₃.

Bis(amido) rare-earth complexes coordinated by tridentate amidinate ligand: synthesis, structure and catalytic activity in the polymerization of isoprene and rac-lactide

Rare-earth bis(amides) {2-[Ph₂Р(O)]C₆H₄NC(tBu)N(2,6-Me₂C₆H₃)}Ln(N(SiMe₃)₂)₂ (Ln = Y, Nd, La) coordinated by tridentate amidinate ligand were synthesized, structurally characterized and evaluated as catalysts for isoprene and rac-lactide polymerizations.

Carbon bridged triphenolate lanthanide complexes: synthesis, characterization, DFT studies and catalytic activities for isoprene polymerization

Lanthanide complexes supported by carbon bridged triphenolate ligands were synthesized and theoretical calculations were carried out on a Lu complex.

The behaviour of β-triketimine cobalt complexes in the polymerization of isoprene

Cobalt complexes of β-triketimines activated by Et₂AlCl polymerize isoprene to give up to 80%cis-1,4 with 20% 3,4 polymer, at 35 °C.