Polymerization Of Butadiene Research Articles

Effect of aging conditions of neodymium‐based catalysts on cis‐1,4 polymerization of butadiene

AbstractThe aim of this work is to evaluate the effect of aging conditions catalysts based on neodymium salt on polymerization conversion, catalyst activity, and polymer characteristics. The synthesized catalysts were aged at 10, 25, 40, and 60°C for 24 and 48 h. The polybutadienes were characterized by size exclusion chromatography to determine the molecular weight characteristics and infrared spectroscopy to determine the microstructure. The results showed that the stereoselectivity of active catalyst sites was not affected by the aging conditions. However, the molecular weight increased with aging temperature. The catalysts aged at 25°C showed a trend to attain higher activities than those aged at 40 and 60°C. Moreover, a significant drop on polymerization reaction rate occurred as the catalyst aging temperature increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Modification of polybutadiene with caprolacton during polymerization

Polybutadiene has been modified with ɛ-caprolacton during butadiene polymerization carried out in the presence of catalytic systems based on neodymium and organoaluminum compounds at a butadiene conversion of 90–96%. The structure, phase state, and temperature behavior of polybutadienes modified with ɛ-caprolacton have been studied by IR and 13C NMR spectroscopy, DSC, and X-ray diffraction analysis. The above approach shows promise for the synthesis of new-generation elastomers which do not rank below conventional rubbers in terms of their characteristics but possess biodegradability.

Kinetic nonuniformity of a titanium catalyst in the polymerization of butadiene: Effect of intensifying stirring of the reaction mixture

Intensification of turbulent stirring of the reaction mixture in the course of butadiene polymerization on a titanium catalyst promotes a successive increase in the rate of reaction with increasing polymer content. Independent of the viscosity of the reaction mixture, the concentration of active centers forming the low-molecular-mass fraction of polybutadiene decreases and the molecular mass distribution narrows. The reactivity distribution of active centers is determined by the hydrodynamic effect, and it does not depend on the increasing viscosity of the reaction mixture. This suggests an insignificant influence of viscosity and, hence, diffusion limitations on the distribution of active centers of polymerization over the probability of chain propagation.

Simulation of butadiene rubber synthesis on cobalt- and neodymium-containing catalytic systems in reactor cascades with heat removal

The synthesis of butadiene rubber on cobalt- and neodymium-containing catalytic systems in a reactor cascade has been simulated taking into account heat removal through the reactor jackets. The problem of optimization of the operating regime has been solved for butadiene polymerization in a cascade of continuous reactors. The regions of initial process parameters admissible for obtaining a high-quality rubber have been determined.

Thiophene-NPN Ligand Supported Rare-Earth Metal Bis(alkyl) Complexes. Synthesis and Catalysis toward Highly trans-1,4 Selective Polymerization of Butadiene

A series of new rare-earth metal bis(alkyl) complexes [L1−3Ln(CH2SiMe3)2(THF)n] (L1 = MeC4H2SCH2NC6H4(Ph)2P═NC6H2Me3-2,4,6: Ln = Sc, n = 1 (1a); Ln = Lu, n = 1 (1b); L2 = MeC4H2SCH2NC6H4(Ph)2P═NC6H3Et2-2,6: Ln = Sc, n = 1 (2a); Ln = Lu, n = 1 (2b); Ln = Y, n = 1 (2c); L3 = MeC4H2SCH2NC6H4(Ph)2P═NC6H3iPr2-2,6: Ln = Sc, n = 0 (3a)) and L4Sc(CH2SiMe3)2(THF) (4a) (L4 = C6H5CH2NC6H4(Ph)2P═NC6H3Et2-2,6) have been prepared by reaction of rare-earth metal tris(alkyl)s with the corresponding HL1−4 ligands via alkane elimination. Complexes 1a, 1b, 2a−2c, and 4a are monomeric with a coordinating THF molecule. Each metal ion is coordinated by a NPN ligand, two trans-located alkyl groups, and a THF molecule, forming a distorted trigonal-bipyramidal geometry. Complex 3a is THF-free, adopting a distorted tetrahedron geometry. In combination with AlR3 and borate, these complexes have shown medium activity and good trans-1,4 selectivity for the polymerization of butadiene. The resultant polymer has moderate molecular weig...

Catalytic Polymerization of Butadiene in Aqueous Systems with Cationic Nickel(II) Complexes

The cationic nickel(II) complexes ((η 3 -C3H5)Ni(SbPh3)2)(B(3,5-(CF3)2C6H3)4 )( 2) and ((η 3 - C3H5)Ni(SbPh3)2)(Al(OC(CF3)3)4 )( 3) were prepared and their polymerization activities in aqueous systems were compared with ((η3-C3H5)Ni(η6-BHT))(B(3,5-(CF3)2C6H3)4 )( 1) (BHT ) 3,5-di-tert-butyl-4-hydroxytoluene). Cis- polybutadiene is formed in nonaqueous solution polymerization. The presence of water decreases activity and polymer molecular weight and increases trans incorporation of butadiene units. In emulsion polymerization, stable polymer dispersions can be obtained with complex 2 and 3, respectively. The microstructure is strongly altered by comparison to nonaqueous polymerization. Trans-polybutadiene is formed with activities of up to 1.5 × 103 mol (butadiene) mol (Ni)-1 h-1. The semicrystalline latex particles have sizes of ca. 200 nm, with a monoclinic structure.

Synthesis and physicochemical characterization of a well-defined poly(butadiene 1,3)-block-poly(dimethylsiloxane) copolymer

For the first time, order–order and order–disorder transitions were detected and characterized in a model diblock copolymer of poly(butadiene-1,3) and poly(dimethylsiloxane) (PB-b-PDMS). This model PB-b-PDMS copolymer was synthesized by the sequential anionic polymerization (high vacuum techniques) of butadiene 1,3 (B) and hexamethylciclotrisiloxane (D3), and subsequently characterized by nuclear magnetic resonance (1H and 13C NMR), size exclusion chromatography (SEC), Fourier Transform infrared spectroscopy (FTIR), Small-Angle X-ray scattering (SAXS) and rheology. SAXS combined with rheological experiments shows that the order–order and order–disorder transitions are thermoreversible. This fact indicates that the copolymer has sufficient mobility at the timescale and at the temperatures of interest to reach their equilibrium morphologies.

Activity of butadiene polymerization centers at in situ formation of titanium catalysts

Directional action on the activity of macromolecule propagation centers and their typical set in synthesis of stereoregular polydienes in the presence of polycentered Ziegler-Natta catalytic systems allows control over the molecular characteristics of the polymers obtained and over the service characteristics of products thereof.

Hydrodynamic effect on the heterogeneity of active sites of butadiene polymerization upon formation of titanium catalyst in situ

The effect of hydrodynamic conditions of the reaction mixture flow during formation of active sites sites of butadiene polymerization on their distribution by kinetic and stereospecific heterogeneity was studied. The enhanced intensity of the turbulent mixing at the stage of formation of active sites results in lowering of the number of types of active sites of chain propagation and the polydispersity coefficient with changes in stereoregular composition of polybutadiene.

Neodymium Ziegler–Natta catalysts: Evaluation of catalyst ageing effect on 1,3-butadiene polymerization

Catalysts constituted by neodymium versatate, diisobutylaluminium hydride and t-butyl chloride were used in this work. After their synthesis, they were aged at 40 °C for 48 h. Afterwards, they were maintained at 10 °C for more 5, 15, 40, 80, 160 and 250 days and finally the aged catalysts were evaluated in butadiene polymerization. The polybutadienes were characterized by size exclusion chromatography (SEC) to determine the molecular weight characteristics and by infrared spectroscopy (FTIR) to determine the microstructure. The aim of this work is to evaluate the effect of ageing time on 1,4 polymerization of butadiene. The results showed that the stereoselectivity of the active sites was not affected by the ageing conditions. However, the catalyst activity increased for long times of ageing.

Polymerization of butadiene with a halogen-containing trans-regulating neodymium-magnesium catalytic system in the presence of carbon tetrachloride

The polymerization of butadiene in toluene initiated by the NdCl3 · 3TBP-Mg(C4H9)(i-C8H17) (TBP is tributyl phosphate) catalytic system has been studied. It has been shown that the polymerization reaction under study is a nonstationary slowly initiated process. The addition of carbon tetrachloride promotes an increase in the catalytic activity of the system. The products of polymerization have low molecular masses and polydispersity indexes. The content of 1,4-trans-units in the polymer is as high as 95%.

Neutral and Monocationic Half‐Sandwich Methyl Rare‐Earth Metal Complexes: Synthesis, Structure, and 1,3‐Butadiene Polymerization Catalysis

AbstractHalf‐sandwich rare‐earth metal tetramethylaluminate complexes [Ln(η5‐C5Me4SiMe3){(μ‐Me)2(AlMe2)}2] (Ln = Y, La, Nd, Sm, Gd, Lu) were obtained by reaction of the neutral homoleptic tetramethylaluminate complex [Ln{(μ‐Me)2(AlMe2)}3] with tetramethyl(trimethylsilyl)cyclopentadiene, (C5Me4H)SiMe3. Protonolysis reaction of the neutral mono(cyclopentadienyl) complexes with the Brønsted acid [NEt3H]+[BPh4]– in thf led to the formation of the monocationic methyl complexes [Ln(η5‐C5Me4SiMe3)Me(thf)3]+[BPh4]– (Ln = Y, La, Nd, Sm, Lu). Single‐crystal X‐ray diffraction study on the Y, Sm, and Lu derivatives showed a four‐legged piano‐stool configuration. Upon activation with [Ph3C]+[B(C6F5)4]–, the neutral half‐sandwich tetramethylaluminate complex [La(η5‐C5Me4SiMe3){(μ‐Me)2(AlMe2)}2] catalyzed the polymerization of butadiene in the presence of [AliBu3] to give trans‐1,4‐polybutadiene with narrow polydispersities (Mn/Mw = 1.05–1.09).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Mechanistic Insight into the Polymerization of Butadiene by “Ligand-Free” Polybutadienyl−Nickel(II) Complexes: Computational Assignment of the True Structure of the Resting State

DFT calculations have unveiled the true structure of the catalyst resting state of butadiene polymerization by “ligand-free” polybutadienyl−nickel(II) complexes and have rationalized the origin of ...

Scandium complexes with [N,N,Cp] and [N,N,O] donor-set ancillary ligands as catalysts in olefin polymerization

New Sc(III) chloro-complexes [ScCl 2(NNCp)(THF)] ( 1), [ScCl 2(NNO)(THF)] ( 2) and [ScCl 2(NNHO)(THF)] ( 3) {NNCp = 6-cyclopentadienylmethyl-pyridin-2-ylmethylene)-(2,6-diisopropyl-phenyl)-amine; NNO = 2- tert-butyl-6-((quinolin-8-ylimino)methyl)phenolate); NNHO = 2- tert-butyl-6-((quinolin-8-ylamino)methyl)phenolate} have been synthesized and characterized by NMR and mass spectrometry. The comparative results of the catalytic behavior of these scandium complexes towards ethylene and butadiene polymerization are reported and explained on the basis of the electronic and steric properties of the ancillary ligands.

Highly cis-1,4 Selective Polymerization of Dienes with Homogeneous Ziegler−Natta Catalysts Based on NCN-Pincer Rare Earth Metal Dichloride Precursors

The first aryldiimine NCN-pincer ligated rare earth metal dichlorides (2,6-(2,6-C6H3R2N=CH)2-C6H3)LnCl2(THF)2 (Ln = Y, R = Me (1), Et (2), iPr (3); R = Et, Ln = La (4), Nd (5), Gd (6), Sm (7), Eu (8), Tb (9), Dy (10), Ho (11), Yb (12), Lu (13)) were successfully synthesized via transmetalation between 2,6-(2,6-C6H3-R2N=CH)2-C6H3Li and LnCl3(THF)(1-3.5). These complexes are isostructural monomers with two coordinating THF molecules, where the pincer ligand coordinates to the central metal ion in a kappaC:kappaN:kappaN' tridentate mode, adopting a meridional geometry. Complexes 1-6, 9-11, and 13 combined with aluminum tris(alkyl)s and [Ph3C][B(C6F5)4] established a homogeneous Ziegler-Natta catalyst system, which exhibited high activities and excellent cis-1,4 selectivities for the polymerizations of butadiene (T(p) = 25 degrees C, 99.9%; 0 degrees C, 100%) and isoprene (T(p) = 25 degrees C, 98.8%). Remarkably, such high cis-1,4 selectivity almost remained at elevated polymerization temperatures up to 80 degrees C and did not vary with the type of the central lanthanide element, however, which was influenced obviously by the ortho substituent of the N-aryl ring of the ligands and the bulkiness of the aluminum alkyls. The Ln-Al bimetallic cations were considered as the active species. These results shed new light on improving the catalytic performance of the conventional Ziegler-Natta catalysts for the specific selective polymerization of dienes.

ジエン重合における最近の動向

This review describes polymerizations of dienes such as butadiene and isoprene with radical initiators, anionic initiators and transition metal complexes with respect to recent development. In radical polymerizations, living radical polymerizations are applied to polymerization of butadiene, and the living polymerization of butadiene gave narrow molecular weights and α, ω-difunctional polymers, leading to the formation of cyclic polybutadiene by ring closure reaction using both chain ends. In anionic polymerizations, functionalizations of polymers at the chain end and inchain have been developed by use of living anionic polymerization initiator and functional monomers. Many block copolymers including polybutadiene segment are synthesized and characterized. In transition metal complexes catalyzed polymerizations, a simultaneous control of 1, 4-cis selectivity and molecular weight of the polymers was achieved in the polymerization of butadiene. In the polymerization of isoprene, a precision polymerization is also achieved using lanthanide complexes. Cyclic polybutadiene was synthesized by ring opening metathesis polymerization (ROMP) of cyclooctadiene by the well designed Ru-based catalyst. The polymer obtained from ROMP consists of only 1, 4-structure.

チタン錯体触媒による炭化水素系モノマーのリビング重合

This review article summarizes living polymerization of hydrocarbon monomers with titanium-based catalysts. The first part summarizes the past research results in living polymerization of olefins, such as higher a-olefins, propylene and ethylene. The recent developments of vinyl addition living polymerization of cycloolefins, such as norbornene and their copolymerization with ethylene or propylene were introduced in the second part. In the last part, the research achievements for living polymerization of styrene and butadiene were also summarized. The synthesis of block copolymers by applying the characteristic of those living systems was also described in each part.

Simultaneous Control of Molecular Weight and 1,4-Cis Selectivity in the Polymerization of 1,3-Butadiene with N,N′-Diphenyl and 3,3′,5,5′-tetra-t-Butyl Substituted (Salen)Co(II) Complex

Controlled 1,4-cis specific polymerization of butadiene (Bd) with N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediaminato cobalt (1), in combination with methylaluminoxane (MAO) was investigated. 1/MAO catalyst showed the high activity for the polymerization of Bd. In the polymerization of Bd with 1/MAO catalysts in CH2Cl2 at −30°C, the molecular weight of the polymer increased linearly with an increase of polymer yield, and the line passed through the origin. Moreover, the molecular weight distribution of the polymer was narrow (Mw/Mn=1.29) and microstructure was a high 1,4-cis content (~98%). The results demonstrate that a simultaneous control of 1,4-cis selectivity and the molecular weight of the polymer can be achieved in the polymerization of Bd with the (salen)Co(II) having t-butyl groups at 3,3′,5,5′-positions in the aromatic ring and phenyl groups at N,N′-positions in combination with MAO.

Chromium Catalysts for Butadiene and Norbornene Polymerization

AbstractA new class of chromium catalysts were obtained by combining bidentate phosphine chromium(II) complexes with methylaluminoxanes. These systems were found to be very active in the polymerization of butadiene giving 1,2 polymers having different tacticity (iso or syndio) depending on the type of phosphine bonded to the chromium atom. Moreover, they were also able to polymerize norbornene, giving crystalline all exo‐enchained vinyl addition polymers, exhibiting a rather unusual structure in the field of olefin stereospecific polymerization, namely diheterotactic structure, characterized by regular sequences of (mr) atactic triads.

Copolymerization of Styrene with Butadiene and Isoprene Catalyzed by the Monocyclopentadienyl Titanium Complex Ti(η5-C5H5)(η2-MBMP)Cl

Polymerization of butadiene, isoprene, and styrene was investigated using the catalyst Ti(η5-C5H5)(η2-MBMP)Cl (1) (MBMP = 2,2‘-methylenebis(6-tert-butyl-4-methylphenoxo)) activated with methylaluminoxane (MAO). Syndiotactic polystyrene and cis-1,4-polybutadiene were obtained at 50 °C, similarly to other monocyclopentadienyl titanium catalysts previously reported. On the contrary, the 1/MAO catalyst resulted extremely active in isoprene polymerization, producing polymers with mainly cis-1,4 structure and containing head-to-head and tail-to-tail enchainments of the monomer units in a molar concentration of 21.5%. Binary copolymerization of styrene with butadiene yielded block copolymers containing segments of cis-1,4-polybutadiene and crystalline syndiotactic polystyrene. The reactivity ratios r1 = 70 and r2 = 1.2 determined by NMR methods confirmed the blocky distribution of the monomers in the copolymer chain. The AFM of copolymers rich in styrene (xS = 0.77−0.81) showed a microphase separation of polybut...