Synthesis of high molecular weight copolymer of styrene and butadiene bearing high 1,4‐cis butadiene unit from copolymerization with CpTiCl3/methylaluminoxane catalyst

Copolymerization of styrene (St) and butadiene (Bd) with CpTiCl₃/methylaluminoxane (MAO) catalyst in the presence or absence of chloranil (CA) was investigated. The CpTiCl₃/MAO catalyst showed a high activity for the copolymerization of St with Bd. The 1,4‐cis contents in the Bd units for the copolymerization of St and Bd with the CpTiCl₃/MAO catalyst was observed, and the 1,4‐cis content was optimum at a MAO/Ti mole ratio of around 225. The effect of the polymerization temperature on the copolymerization was noted, as was the effect of the 1,4‐cis microstructure in the Bd units for the copolymerization of St and Bd. The addition of CA to the CpTiCl₃/MAO catalyst was found to influence the molecular weight of the copolymer. The high weight‐average molecular weight copolymer (M_w = ca. 50 × 10⁴) consisting of mainly a 1,4‐cis microstructure of Bd units (1,4‐cis = 80.0%) was obtained from the copolymerization with the CpTiCl₃/MAO catalyst in the presence of CA (CA/Ti mole ratio = 1) at 0°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2942–2946, 2003     

Polymerization of butadiene and copolymerization of butadiene with styrene using neodymium amide catalysts

The polymerization of butadiene was performed with catalysts based on the complex Nd{N(SiMe₃)₂}₃ (1). This amide complex in combination with methyaluminoxane or with a boron compound ([HNMe₂Ph][B(C₆F₅)₄], [CPh₃][B(C₆F₅)₄] or B(C₆F₅)₃) and Al(iBu)₃ showed high activity and stereospecificity in polymerization of butadiene. The cationic complex [Nd{N(SiMe₃)₂}₂(THF)₂][B(C₆F₅)₄] (2) was prepared by reaction of 1 and [HNMe₂Ph][B(C₆F₅)₄]. The catalyst 2/Al(iBu)₃ (ratio Al/Nd: 10/1) was highly active for butadiene polymerization. Copolymerization of butadiene and styrene was performed with the catalytic system Nd{N(SiMe₃)₂}₃/[HNMe₂Ph][B(C₆F₅)₄]/Al(iBu)₃ (3). Copyright © 2004 Society of Chemical Industry     

Copolymerization of butadiene with styrene using a rare‐earth metal compound – dialkylmagnesium – halohydrocarbon catalytic system

Copolymerizations of butadiene (Bd) with styrene (St) were carried out with catalytic systems composed of a rare‐earth compound, Mg(n‐Bu)₂ (di‐n‐butyl magnesium) and halohydrocarbon. Of all the rare earth catalysts examined, Nd(P₅₀₇)₃–Mg(n‐Bu)₂–CHCl₃ showed a high activity in the copolymerization under certain conditions: [Bd] = [St] = 1.8 mol l^?1, [Nd] = 6.0 × 10^?3 mol l^?1, Mg/Nd = 10, Cl/Nd = 10 (molar ratio), ageing for 2 h, copolymerization at 50 °C for 6–20 h. The copolymer of butadiene and styrene obtained has a relatively high styrene content (10–30 mol%), cis‐1,4 content in butadiene unit (85–90%), and molecular weight ([η] = 0.8–1 dL g^?1). Monomer reactivity ratios were estimated to be r_Bd = 36 and r_St = 0.36 in the copolymerization. © 2002 Society of Chemical Industry     

Preliminary investigations on polymerization catalysts composed of lanthanocene and methylaluminoxane

Summary The polymerization of butadiene(Bd), isoprene(Ip) and styrene(St) has been examined using the six catalyst systems composed of lanthanocene, (C₅H₉Cp)₂NdCl(I), (C₅H₉Cp)₂SmCl(II), (MeCp)₂Sm OAr'(III), (Ind)₂NdCl(IV), Me₂Si(Ind)₂NdCl(V) and (Flu)₂NdCl(VI), and methylaluminoxane(MAO) respectively. All of them can be used to form the polyisoprene with molecular weights of 1 to 10 thousand and cis-1,4-unit contents of 41 to 47%. (I), (II) and (III) of them can be also used to form the polybutadiene with molecular weights of 10 to 20 thousand and cis-1,4-unit contents of 62 to 78%. In addition, the catalysts from (II) to (V) are still active for St polymerization and (II) of them gives a syndio -rich random polystyrene. It is noteworthy that (II) and (III) are active for homopolymerization of Bd, Ip and St in the same polymerization condition. Received: 16 December 1997/Revised version: 17 March 1998/Accepted: 24 March 1998     

Polymerization of methyl methacrylate with Ni(acac)2–methylaluminoxane catalyst

Polymerization of methyl methacrylate (MMA) with nickel(II) acetylacetonate [Ni(acac)₂] in combination with methylaluminoxane (MAO) was investigated. Ni(acac)₂ was found to be an effective catalyst for the polymerization of MMA. From a kinetic study of the polymerization of MMA with the Ni(acac)₂–MAO catalyst, the overall activation energy was estimated to be 15 kJmol⁻¹. The polymerization rate (R_p) was expressed as follows: R_p = k [MMA]^1.0[Ni(acac)₂–MAO]^0.6 (the MAO/Ni mole ratio was kept constant). The mechanism for the polymerization of vinyl monomers with the Ni(acac)₂–MAO catalyst is discussed. © 2000 Society of Chemical Industry     

Polymerization of styrene using pyrazolylimine nickel (II)/methylaluminoxane catalytic systems

The polymerization of styrene with two pyrazolylimine nickel (II) complexes of (2-(C₃HN₂Me₂-3, 5)(C(Ph) = N(4-R₂C₆H₂(R₁)₂-2, 6)NiBr₂ (Complex 1 , R₁ = ⁱPr, R₂ = H; Complex 2 , R₁ = H, R₂ = NO₂)) activated by methylaluminoxane was studied. The influences of polymerization parameters such as polymerization temperature, Al/Ni molar ratio, and reaction time on catalytic activity and molecular weight of the polystyrene (PS) were investigated in detail. The electron-withdrawing of nitro group in Complex 2 could not enhance the catalytic activity for styrene polymerization; however, the molecular weights of polymers were increased. Both of the two catalytic systems exhibited high activity [up to 8.45 × 10⁵ gPS/(mol Ni h)] for styrene polymerization and provide PS with moderate to low-molecular weights (M_w = 2.21 × 10⁴∼ 5.71 × 10³ g/mol) and narrower molecular weight distributions about 2.0. The obtained PS were characterized by means of IR, ¹H NMR, and ¹³C NMR techniques. The results indicated that the PS was atactic polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Styrene–substituted‐styrene copolymerization using diphenylzinc–metallocene–methylaluminoxane systems

Homopolymerization of disubstituted styrenes (2,4‐ and 2,5‐dimethylstyrene) and trisubstituted styrene (2,4,6‐trimethylstyrene) and their copolymerization with styrene were carried out using diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n‐BuCp)₂TiCl₂ and for half‐metallocene CpTiCl₃. The studied comonomers were found to be less reactive than p‐tertbutylstyrene, p‐methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di‐ and tri‐methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry     

1,2‐Polymerization of 1,3‐butadiene with Cr(acac)3‐alkylaluminum catalysts

The polymerization of butadiene (Bd) with chromium(III) acetylacetonato [Cr(acac)₃]‐trialkylaluminum (AlR₃) or methylaluminoxane (MAO) catalysts was investigated for the synthesis of 1,2‐poly(Bd). The polymerization of Bd was found to proceed with Cr(acac)₃‐AlR₃ (R‐Me, Et, i‐Bu) catalysts to give poly(Bd) with a high 1,2‐vinyl content, but highly isotactic 1,2‐poly(Bd) was not synthesized. The Cr(acac)₃‐MAO catalyst gave a polymer consisting of low 1,2 units. The effects of the Al/Cr mole ratios on the polymerization of Bd with the Cr(acac)₃‐AlR₃ catalysts were observed. With an increase of Al/Cr mole ratios, the isotactic (mm) content of the polymer increased but the 1,2‐vinyl contents decreased. The effects of the aging time and temperatures of the catalysts on the polymerization of Bd with the Cr(acac)₃‐AlR₃ catalysts were also observed, and the lower polymerization temperature and the prolonged aging time were favored to produce the 1,2‐vinyl structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1621–1627, 2000     

Modelling studies of the controlled anionic copolymerization of butadiene and styrene

The anionic polymerization of isoprene with n-butyl lithium and polar modifier such as TMEDA and tripiperdinophosphine oxide were studied and kinetic and reactor models are proposed for these systems. Reactor conversion, molecular weight distribution and polymer glass transition temperature had been calculated from the model and compared favorably to the actual data for various combinations of reactor systems and operating conditions. Simulations of the model can be used to design reactor systems and predict polymer properties of large-scale operations from results of small scale batch reactor runs.     

Effects of 1,2‐butadiene on the anionic copolymerization of styrene and 1,3‐butadiene in the presence of polar additives

1,2‐Butadiene is shown to be a chain terminating/transferring agent in butyllithium‐initiated diene polymerization. The influence of 1,2‐butadiene on the anionic copolymerization of 1,3‐butadiene and styrene is investigated using n‐butyllithium as initiator and tetrahydrofuran or N,N,N′,N′‐tetramethylethylenediamine as polar additive. A decrease of copolymerization rate is observed on the addition of 1,2‐butadiene. On introducing 1,2‐butadiene, the number average molecular weight (M_n ) decreases and the molecular weight distribution broadens. The vinyl content of copolymer increases slightly with an increase of 1,2‐butadiene. During the copolymerization, 1,2‐butadiene in the presence of a high ratio of polar additives to n‐butyllithium greatly decreases the copolymerization rate, resulting in a lower value of M_n and a narrower molecular weight distribution than that found for a low ratio of polar additives to n‐butyllithium. This evolution can be explained by the base‐catalyzed isomerization of 1,2‐butadiene to form 1‐butylene in the presence of polar additives. With an increasing amount of 1,2‐butadiene, the vulcanized rubber exhibits an increased rolling resistance and a reduced wet skid resistance owing to the decrease of coupling efficiency. These results further indicate the activity of alkynyllithium derivatives produced by the reaction of alkyllithium and 1‐butyne is less than that of the alkyllithium. Copyright © 2007 Society of Chemical Industry     

Grafting of N‐carbamyl maleamic acid onto a styrene–butadiene–styrene copolymer

A styrene–butadiene–styrene block copolymer (SBS) was functionalized with N‐carbamyl maleamic acid (NCMA) using two peroxide initiators with the aim of grafting polar groups onto the molecular chains of the polymer. The influence of the concentration of benzoyl peroxide (BPO) and 2,5‐dimethyl, 2,5‐diterbuthylperoxihexane (DBPH) was studied. The concentration of peroxy groups ranged between 0.75 and 6 × 10^?4 mol % while the concentration of NCMA was constant at 1 wt %. The reaction temperature was chosen according to the type of peroxide employed, being 140°C for BPO and 190°C for DBPH. FTIR spectra confirmed that NCMA was grafted onto the SBS macromolecules. It was found that the highest grafting level was achieved at a concentration of peroxy groups of about 3 × 10^?4 mol %. Contact angle measurements were used to characterize the surface of the SBS and modified polymers. The contact angle of water drops decreased with the amount of NCMA grafted from 95°, the one corresponding to the SBS, to about 73°. T‐peel strength of polymer/polyurethane adhesive/polymer joints made with the modified polymers was larger than those prepared with the original SBS. The peel strength of SBS modified with 1.5 and 3 × 10^?4 mol % of peroxy groups from BPO were five times larger than that of the original SBS. The materials modified using BPO showed peel strengths higher than the ones obtained with DBPH. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4468–4477, 2006     

Homopolymerization and copolymerization of tert‐butyl methacrylate and norbornene with nickel‐based methylaluminoxane catalysts

The homopolymerization and copolymerization of tert‐butyl methacrylate (tBMA) and norbornene (NB) with nickel(II) acetylacetonate in combination with methylaluminoxane were systematically investigated. This catalytic system showed high activity toward the homopolymerization of both NB and tBMA. For these copolymerizations, activity was gradually lost with an addition of tBMA to NB or of NB to tBMA. This result was qualitatively explained with the trigger coordination mechanism. Furthermore, the determination of the reactivity ratios indicated a significantly higher reactivity for NB than for tBMA (r_NB = 4.14 and r_tBMA = 0.097), and this was interpreted by the coordination mechanism. The synthesized acrylate/NB copolymers exhibited glass‐transition temperatures of 100–250°C. The absence of crystallinity and the homogeneous repartition of the monomer units along the main chain yielded products with high transparency and high stability © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1824–1833, 2004     

Effect of bonding agents on styrene butadiene rubber–aluminum powder composites

Effects of various bonding agents—such as the hexamethylene tetramine–resorcinol system (HR), bis[3‐ (triethoxysilyl) propyl] tetra sulfide (Si‐69), and cobalt naphthenate (CoN)—on the mechanical properties of aluminum powder filled styrene butadiene rubber composites were studied, giving emphasis on concentration of bonding agent and loading of aluminum powder. Shore A hardness, modulus, tensile strength, tear strength, heat buildup, etc., were increased by the loading of aluminum powder, and the presence of bonding agents again increased these properties. Rebound resilience and elongation at break were decreased by the addition of aluminum powder. Equilibrium swelling studies showed an improved adhesion between aluminum powder and styrene butadiene rubber (SBR) in presence of bonding agents. Among the various bonding agents used in this study, silane coupling agent (Si‐69) and hexamethylene tetramine–resorcinol (HR) system were found to be better for aluminum powder filled SBR vulcanizates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 519–529, 2002     

丁苯嵌段共聚物的催化氢化研究进展

介绍了丁苯嵌段共聚物的催化加氢技术，综述了茂金属催化剂，环烷酸镍（钴）催化剂，三苯基膦-氯化钌（铑），铁钴镍螯合物均相催化剂及非均相催化剂的技术进展。讨论了氢化丁苯嵌段共聚物氢化度的定性分析和定量分析方法。     

丁苯橡胶生产及市场分析

综述了国内外丁苯橡胶（SBR）的生产及市场情况,对国内SBR的市场发展趋势进行了分析。并预测在世界金融危机的影响下,国内SBR需求增长将会放缓,而国内产能的猛增,将加剧SBR产能过剩,造成供过于求的局面。此外,本文还对国内SBR行业存在的不足提出了几点建议。     

丁苯橡胶生产及市场分析

综述了国内外丁苯橡胶的生产及市场情况,对国内丁苯橡胶的市场发展趋势进行了分析。此外,还对国内丁苯橡胶行业存在的不足提出了几点建议。     

Polymerization of 1,3‐butadiene with VO(P204)2 activated by methylaluminoxane,purified methylaluminoxane,and trimethylaluminum

The effect of different aluminum‐based cocatalysts (MAO, pMAO, and TMA) on butadiene (Bd) polymerization catalyzed by VO(P204)2 was investigated. The bimodal dependence of the polymer yield on the [MAO]/[V] molar ratio was revealed, and an highest polymer yield was achieved at a rather low [MAO]/[V] molar ratio ([MAO]/[V] = 13). The microstructures of the resulting poly(Bd)s were also significantly influenced by the ratio. In the TMA or pMAO system, the polymer yields were also very sensitive to the [Al]/[V] molar ratio. However, the microstructures of the resulting poly(Bd)s were almost independent of the ratio. In relation to the microstructures of poly(Bd)s obtained by the MAO and TMA systems at various temperatures, the 1,2‐unit contents were found to be the most abundant microstructure for both systems. In the pMAO system, the trans‐1,4‐units were the most abundant. The results of the additions of Lewis bases (THF and TPP) into Bd polyerization system comfirmed the existing of the two types of the reactions of VO(P₂₀₄)₂‐MAO catalyst and had the polymerization process controlled to some extent. The different thermal behaviors of these catalytic systems also show that multiple types of active centers were formed during the reaction between VO(P₂₀₄)₂ and MAO. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel monotitanocene and methylaluminoxane catalyst for syndiospecific polymerization of styrene

Syndiotactic polystyrene (sPS) was synthesized with a novel monotitanocene complex of η⁵‐pentamethylcyclopentadienyltri‐4‐methoxyphenoxy titanium [Cp*Ti(OC₆H₄OCH₃)₃] activated by methylaluminoxane (MAO) in different polymerization media, including heptane, toluene, chlorobenzene, and neat styrene. In all cases bulk polymerization produced sPS with the highest activity and molecular weight. Solution polymerization produced much better activity in heptane than in the other solvents. Using a solvent with a higher dipole moment, such as chlorobenzene resulted in lower activity and syndiotacticity because of the stronger coordination of solvent with the Ti(III) active species, which controlled syndiospecific polymerization of styrene. With bulk polymerization at a higher polymerization temperature the Cp*Ti(OC₆H₄OCH₃)₃–MAO catalyst produced sPS with high catalytic activity and molecular weight. The external addition of triisobutylaluminum (TIBA) to the Cp*Ti(OC₆H₄OCH₃)₃–MAO system catalyzing styrene polymerization led to significant improvement of activity at a lower Al:Ti molar ratio, while the syndiotacticity and molecular weight of the yields were little affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1243–1248, 2001     

Interfacially confined RAFT miniemulsion copolymerization of styrene and butadiene

In this study, ammonolyzed poly(styrene‐alt‐maleic anhydride) terminated with dithioester group can be self‐assembled into an amphiphilic macro‐reversible addition‐fragmentation chain transfer (RAFT) agent, and RAFT group will be located in the interface of oil and water. RAFT polymerization of styrene (S) and butadiene (B) will be confined in the interface. The main work is to study the effect of degree of aminolysis, reaction temperature, and ratio of S/B on the polymerization kinetics and living characters. The experimental results revealed that aminolysis of dithioester group would lead to retardation and loss of living characters under higher degree of aminolysis. Interfacially confined RAFT miniemulsion polymerizations were of relatively good controlled/living characters under lower degree of aminolysis before gelation. Increase of reaction temperature and ratio of S/B will accelerate the formation of gelation. Finally, styrene/butadiene copolymer nanoparticles with uniform particle size were formed, and because of microphase segregation “core–shell” morphology with polybutadiene core and polystyrene shell was seen obviously. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polymerization of styrene using novel bispyrazolylimine dinickel (II)/methylaluminoxane catalytic systems

The polymerization of styrene with a series of bispyrazolylimine dinickel (II) complexes of bis‐2‐(C₃HN₂(R₁)₂‐3,5)(C(R₂) = N(C₆H₃(CH₃)₂‐2,6)Ni₂Br₄ (complex 1 : R₁ = CH₃, R₂ = Ph; complex 2 : R₁ = CH₃, R₂ = 2,4,6‐trimethylphenyl; complex 3 : R₁ = R₂ = Ph; complex 4 : R₁ = Ph, R₂ = 2,4,6‐trimethylphenyl) in the presence of methylaluminoxane (MAO) was studied. The influences of polymerization parameters such as polymerization temperature, Al/Ni molar ratio, reaction time, and catalyst concentration on catalytic activity and molecular weight of the polystyrene were investigated in detail. The influence of the bulkiness of the substituents on polymerization activity was also studied. All of the four catalytic systems exhibited high activity (up to 10.50 × 10⁵ gPS/(mol Ni h)) for styrene polymerization and provide polystyrene with moderate to low molecular weights (M_w = 4.76 × 10⁴–0.71 × 10⁴ g/mol) and narrower molecular weight distributions about 2. The obtained polystyrene was characterized by means of FTIR, ¹H‐NMR, and ¹³C‐NMR techniques. The results indicated that the polystyrene was atactic polymer. The analysis of the end groups of polystyrene indicated that styrene polymerization with bispyrazolylimine dinickel complexes/MAO catalytic systems proceeded through a coordination mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.