Semibatch Terpolymerization of Ethylene, Propylene, and 5-Ethylidene-2-norbornene: Heterogeneous High-Ethylene EPDM Thermoplastic Elastomers

Fully tuneable ethylene-propylene elastomers using a supported permethylindenyl-phenoxy (PHENI*) catalyst

Using a highly active supported permethylindenyl-phenoxy (PHENI*) titanium catalyst, high molecular weight ethylene-propylene (EPM) and ethylene-propylene-diene (EPDM) elastomers are prepared using slurry-phase catalysis. Final copolymer composition was found to reflect the monomer feed ratio in a linear fashion, to access a continuum of material properties with a single catalyst. Post-polymerisation crosslinking of EPDM was also demonstrated in a model sulfur vulcanisation system.

Critical conditions for liquid chromatography of statistical polyolefins: Evaluation of diene distribution in EPDM terpolymers

Liquid chromatography at critical conditions is of interest as it may unravel molecular information on macromolecular structures not accessible by any other analytical techniques. Yet so far, such conditions have never been experimentally established for copolymers, where a particular need for such information exists. Toward this goal, critical conditions for statistical ethylene propylene copolymers were identified. In the first approach the composition of the binary mobile phase was varied at a constant temperature, and secondly by modulating the adsorption-desorption temperature at constant mobile phase composition. Solvents for both methods were identified by using a novel approach that combines structure retention relationships with Hansen Solubility Parameters. As a result, for the first time, the heterogeneity of an ethylene propylene diene terpolymer sample with regard to the pendant double bond of the diene could be determined. The novel chromatographic approach was validated by measuring the composition of fractions taken over the chromatographic run offline by nuclear magnetic resonance. In summary, this work gave the first experimental evidence for the existence of critical conditions for polyolefin random copolymers, as postulated by Brun. This novel chromatographic approach holds immense potential to engineer complex polymers towards future applications by making use of the now-accessible molecular information.

Methods for Predicting Ethylene/Cyclic Olefin Copolymerization Rates Promoted by Single-Site Metallocene: Kinetics Is the Key

In toluene at 50 °C, the vinyl addition polymerization of 4-vinyl-cyclohexene (VCH) comonomers with ethylene is investigated using symmetrical metallocene (rac-Et(Ind)₂ZrCl₂) combined with borate/TIBA. To demonstrate the polymerizations’ living character, cyclic VCH with linear-exocyclic_π and endocyclic_π bonds produces monomodal polymers, but the dispersity (Ɖ) was broader. The copolymers obtained can be dissolved in conventional organic solvent and have excellent thermal stability and crystalline temperature (ΔH_m), and their melting temperature (Tm) varies from 109 to 126 °C, and ΔH_m ranges from 80 to 128 (J/g). Secondly, the distribution of polymeric catalysts engaged in polymer chain synthesis and the nature of the dormant state are two of the most essential yet fundamentally unknown aspects. Comprehensive and exhaustive kinetics of E/VCH have shown numerous different kinetic aspects that are interpreted as manifestations of polymeric catalysts or of the instability of several types of active center [Zr]/[C*] fluctuations and formation rates of chain propagation R_pE, R_pVCH, and propagation rate constants k_pE and k_pVCH, the quantitative relationship between R_pE, R_pVCH and k_pE, k_pVCH and catalyst structures, their constituent polymer Mw, and their reactivity response to the endocyclic and exocyclic bonds of VCH. The kinetic parameters R_pE, R_pVCH, k_pE, and k_pVCH, which are the apparent rates for the metallocene-catalyzed E/VCH, R_pE, and kpE values, are much more significant than R_pVCH and kpVCH at 120 s, R_pE and R_pVCH 39.63 and 0.78, and the k_pE and kpVCH values are 6461 and 93 L/mol·s, respectively, and minor diffusion barriers are recommended in the early stages. Compared with previously reported PE, R_pE and k_pE values are 34.2 and 7080 L/mol·s. VCH increases the R_pE in the initial stage, as we are expecting; this means that the exocyclic bond of VCH is more active at the initial level, and that the chain transfer reaction of cyclic internal π double is increased with the reaction time. The t_p versus R_p, k_p, and [Zr]/[C*] fraction count may be fitted to a model that invokes deactivation of growing polymer chains. At t_p 120–360 s higher, the incorporation rate of VCH suppresses E insertion, resulting in reduced molecular weight.

Design and synthesis of binuclear vanadium catalysts for copolymerization of ethylene and polar monomers

Binuclear vanadium complexes exhibited higher activity than monometallic complexes in ethylene polymerization and afforded UHMWPE. The binuclear catalysts also showed moderate activity in copolymerization with 10-undecen-1-ol and methyl 10-undecenoate.

Highly efficient terpolymerizations of ethylene/propylene/ENB with a half-titanocene catalytic system

Highly efficient terpolymerization of ethylene, propylene and 5-ethylidene-2-norbornene using a half-titanocene containing iminoimidazolidine with methylaluminoxane/Al(iBu)3/2,6-ditertbutyl-4-methyl-phenol was achieved.

Propylene homopolymerization and copolymerization with ethylene by acenaphthene-based α-diimine nickel complexes to access EPR-like elastomers

A series of acenaphthene-based α-diimine nickel complexes were synthesized and subsequently used for accessing branched EPR-like elastomers with different compositions and chain structures.

Biodegradable all polyester-based multiblock copolymer elastomers with controlled properties

A cascade polymerization method is developed here for the synthesis of environmentally-friendly biodegradable all polyester-based thermoplastic elastomers with tunable properties.

Rapid kinetic evaluation of homogeneous single-site metallocene catalysts and cyclic diene: how do the catalytic activity, molecular weight, and diene incorporation rate of olefins affect each other?

The kinetics and mechanism of ethylene and cyclic diene 5-ethylidene-2-norbornene (ENB) copolymerization catalyzed by rac-Et(Ind)₂ZrCl₂/[Ph₃C][B(C₆F₅)₄]/triisobutylaluminium (TIBA) were investigated using a quench-labeling procedure using 2-thiophenecarbonyl chloride (TPCC). The E/ENB copolymers were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and ¹H nuclear magnetic resonance (NMR) spectroscopy and sulfur analysis. To reduce the errors of the ethylene–diene copolymerization for the kinetics study, we selected E/ENB with steric and electronic features that permit us to elucidate the metallocene catalyst behavior against dienes. A quantitative approach of catalyst speciation, stereodynamics, and micro-kinetics assisted the resolution of mechanistic problems, such as the elastomeric synthesis of ethylene propylene diene monomer rubber (EPDM), the catalyst resting state nature, and how much ion-pairing occurs during polymerization. We report here the precise observation of metal–polymer species, explanation of the dynamics of their initiation, propagation, and termination, and ethylene ENB copolymer development. An approach based on acyl chloride was used to selectively quenched transition metal–polymer bonds to evaluate the polymeric catalyst in terms of its reaction rate, R_p, propagation rate content, k_p, and mole fraction of active centers. It is noted that the decline in catalytic activity in the range of 1800 s, and the active center [Zr]/[*C] fraction significantly increased during the initial 1000 s and then tended towards a steady figure of 86%. It is suggested that nearly complete initiation of all olefins catalysts can be obtained after a sufficiently extended reaction. The quick increase in active sites in the first stage can be described by the immediate initiation of active sites positioned on the surfaces of catalyst particles. The initial polymerization rate, R_p, is high and the crystalline properties of the E/ENB copolymer are low due to the greater incorporation of ENB in the polymer backbone, and later the polymerization reaction rates remained stable with a lower mol% of ENB. The melting temperature (T_m) ranges from 108 to 127 °C, whereas the crystalline temperature ranges from 63 to 108 (J g⁻¹). In the E–ENB copolymers, the value of k_pE is much greater than that of k_pENB; at 120 s, the k_pE and k_pENB values are 9115 and 431 L mol⁻¹ s⁻¹, respectively, implying smaller diffusion barriers in the early stages, which are close to the actual propagation rate constant.

The kinetics and mechanism of ethylene and 5-ethylidene-2-norbornene copolymerization catalyzed by rac-Et(Ind)₂ZrCl₂ were investigated using 2-thiophenecarbonyl chloride.