共查询到20条相似文献,搜索用时 11 毫秒
1.
Li Y Voon LT Yeong HY Hijazi AK Radhakrishnan N Köhler K Voit B Nuyken O Kühn FE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(26):7997-8003
Copper(II) complexes with weakly coordinating counter anions can be utilized as highly efficient catalysts for the synthesis of poly(2-methylpropene) ("polyisobutene") with a high content of terminal double bonds. These copper(II) compounds are significantly more active than the manganese(II) complexes described previously, can be applied in chlorine-free solvents such as toluene, are easily accessible, and can be handled at room temperature and in laboratory atmospheres for brief periods, but they are sensitive to excess water, thereby losing their catalytic activity. Replacing the acetonitrile ligands by benzonitrile ligands improves the solubility and catalytic activity in nonpolar and nonchlorinated solvents. However, the benzonitrile copper(II) compounds have lower thermal stability than their acetonitrile congeners. 相似文献
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Seung Uk Son Do Han Kim Il Gu Jung Young Keung Chung Sueg‐Geun Lee Sung‐Ho Chun 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):76-83
New norbornene derivatives synthesized from Pauson–Khand reaction products were homopolymerized and copolymerized with norbornene with an allyl–palladium complex as a catalyst. The ketone group was tolerated by the polymerization reaction. Monomers bearing protected alcohols were easily homopolymerized. Most of the homopolymers were soluble in tetrahydrofuran, CH2Cl2, toluene, and cyclohexane. As the steric bulkiness of the substituent increased, the chain length of the homopolymer decreased. Copolymers with a molecular weight of up to 153,800 were formed and were soluble in tetrahydrofuran, CH2Cl2, toluene, and diethyl ether. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 76–83, 2003 相似文献
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Dong‐Po Song Hong‐Liang Mu Xin‐Cui Shi Yan‐Guo Li Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):562-570
The facile and efficient functionalization of polynorbornene has been achieved through direct copolymerization of norbornene (NB) with 5‐norbornene‐2‐yl acetate (NBA) or 5‐norbornene‐2‐methanol (NBM) using a series of β‐ketiminato Ni(II)‐Me pyridine complexes 1–4 (Scheme 2 ) in the presence of B(C6F5)3. Remarkably, the monomer conversion could reach up to about 96% in 10 min in the NB/NBA copolymerization. The copolymers with wide NBA contents (3.3–38.4 mol %) were obtained by variation of reaction conditions. These copolymers have high molecular weights (MWs) (Mn = 41.8–144 kg/mol) and narrow MW distributions (Mw/Mn = 1.80–2.27). In the absence of alkyl aluminum compounds, a monomer conversion of 81% was observed in the NB/NBM copolymerization, and copolymers with NBM content in the range of 11.2–21.8 mol % were obtained by variation of reaction conditions. In addition, Ni(II)‐Me pyridine complexes 2 was very active at a low B/Ni molar ratio of 6, while bis‐ligand complex 6 bearing the same ligand just showed moderate efficiency at a high B/Ni molar ratio of 20. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
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M. Fernndez‐García M. Fernndez‐Sanz E. L. Madruga 《Journal of polymer science. Part A, Polymer chemistry》2004,42(1):130-136
The free‐radical copolymerization of styrene and butyl acrylate has been carried out in benzene at 50 °C. The lumped k p/k parameter (where k p and k t are the average copolymerization propagation and termination rate constants, respectively) has been determined. Applying the implicit penultimate unit model for the overall copolymerization propagation rate coefficient and the terminal unit effect for the overall copolymerization termination rate coefficient and using the homopolymerization kinetic coefficients, we have found good qualitative agreement between the experimental and theoretical k p/k values. The variation of the copolymerization rate in solution with respect to the values previously found in bulk has been ascribed to a chain length effect on the copolymerization termination rate coefficient. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 130–136, 2004 相似文献
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Toru Doi Akira Akimoto Akikazu Matsumoto Yoshitaka Oki Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1996,34(12):2499-2505
Radical copolymerization of N-(alkyl-substituted phenyl)maleimides (RPhMI) with isobutene (IB) was carried out with an initiator in various solvents at 60°C. The copolymerization of N-(2,6-diethylphenyl)maleimide (2,6-DEPhMI) with IB in benzene proceeded readily in a homogeneous system to give an alternating copolymer over a wide range of the comonomer compositions in the feed. Whereas the alternating tendency of the copolymerization of other RPhMI with IB decreased depending on the alkyl substituents of RPhMI in the following order: 2,6-DEPhMI > N-(2,6-dimethylphenyl)maleimide ≥ N-(2-methylphenyl)maleimide >. N-(4-ethylphenyl)maleimide. The copolymerization reactivities were discussed based on the rate constants for the homo-propagations and cross-propagations. Subsequently, the effect of the solvent on the rate and the reactivity ratios was examined. It was revealed that the copolymerization in chloroform proceeded with higher alternating tendency at a higher copolymerization rate than in the copolymerizations in benzene or dioxane. The copolymers of RPhMI with IB showed excellent thermal stability, i.e., high glass transition temperature and initial decomposition temperature over 200 and 350°C, respectively. © 1996 John Wiley & Sons, Inc. 相似文献
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Junquan Sun Yuhua Shan Yongjin Xu Yonggang Cui H. Schumann M. Hummert 《Journal of polymer science. Part A, Polymer chemistry》2004,42(23):6071-6080
The cyclohexyl‐substituted salicylaldiminato–Ni(II) complex [O? (3‐C6H11)(5‐CH3)C6H2CH?N‐2,6‐C6H3iPr2]Ni(PPh3)(Ph) ( 4 ) has been synthesized and characterized with 1H NMR and X‐ray structure analysis. In the presence of phosphine scavengers such as bis(1,5‐cyclooctadiene)nickel(0) [Ni(COD)2], triisobutylaluminum (TIBA), and triethylaluminum (TEA), 4 is an active catalyst for ethylene polymerization and copolymerization with the polar monomers tert‐butyl‐10‐undecenoate, methyl‐10‐undecenoate, and 4‐penten‐1‐ol under mild conditions. The polymerization parameters affecting the catalytic activity and viscosity‐average molecular weight of polyethylene, such as the temperature, time, ethylene pressure, and catalyst concentration, are discussed. A polymerization activity of 3.62 × 105 g of PE (mol of Ni h)?1 and a weight‐average molecular weight of polyethylene of 5.73 × 104 g.mol?1 have been found for 10 μmol of 4 and a Ni(COD)2/ 4 ratio of 3 in a 30‐mL toluene solution at 45 °C and 12 × 105 Pa of ethylene for 20 min. The polydispersity index of the resulting polyethylene is about 2.04. After the addition of tetrahydrofuran and Et2O to the reaction system, 4 exhibits still high activity for ethylene polymerization. Methyl‐10‐undecenoate (0.65 mol %), 0.74 mol % tert‐butyl‐10‐undecenoate, and 0.98 mol % 4‐penten‐1‐ol have been incorporated into the polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6071–6080, 2004 相似文献
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M. C. Fernndez-Monreal R. Cuervo E. L. Madruga 《Journal of polymer science. Part A, Polymer chemistry》1992,30(11):2313-2319
Ethyl α-hydroxymethylacrylate (EHMA) was polymerized in a 3 mol/L tetrahydrofuran solution at 50°C, using 2–2' azobisisobutyronitrile as initiator. The kinetic behavior indicates a higher polymerization rate for EHMA than for methyl methacrylate (MMA). Copolymerization reaction between MMA and EHMA, under the same experimental conditions, was carried out and values of rMMA = 1.264 and rEHMA = 1.285 were found for the reactivity ratios. The comparison of triad sequences as determined from Bernouillian statistic to those calculated from the experimental spliting of O-methyl and α-methyl 1H-NMR signals of the copolymers confirm the obtained results. © 1992 John Wiley & Sons, Inc. 相似文献
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Carmine Capacchione Daniela Saviello Antonietta Avagliano Antonio Proto 《Journal of polymer science. Part A, Polymer chemistry》2010,48(19):4200-4206
Copolymerization of ethylene with isoprene (IP) catalyzed by 1,4‐dithabutanediyl‐linked bis(phenolato) titanium complexes 1 and 2 and methylaluminoxane (MAO) produced exclusively ethylene‐IP copolymers with good activity. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with IP content ~60%. The copolymer microstructure was fully elucidated by 13C‐NMR spectroscopy of the copolymers with various IP content revealing a strong tendency to the alternating microstructure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4200–4206, 2010 相似文献
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Xiaohui He Yueman Liu Lu Chen Yiwang Chen Defu Chen 《Journal of polymer science. Part A, Polymer chemistry》2012,50(22):4695-4704
A serial of late transition metal complexes, which bearing Benzocyclohexane–ketoarylimine ligand and named as Mt(benzocyclohexane–ketoarylimino)2 {Mt(bchkai)2: Mt=Ni or Pd; bchkai=C10H8(O)CN(Ar)CH3; Ar=naphthyl or fluoryl}, have been synthesized and characterized. The molecular structures of the ligands and nickel complex have been confirmed by X‐ray single‐crystal analyses. The nickel complexes exhibited very high activity up to 2.7 × 105 gpolymer/molNi·h and palladium complexes showed high activity up to 2.3 × 105 gpolymer/molPd·h for norbornene (NB) homo‐polymerization with tris(pentafluorophenyl)borane as cocatalyst. The four complexes were effective for copolymerization of NB and 5‐norbornene‐2‐carboxylic acid methyl ester (NB‐COOCH3) in relatively high activities (0.1–2.4 × 105 gpolymer/molMt·h) and produced the addition‐type copolymers with relatively high molecular weights (0.5 × 105–1.2 × 105 g/mol) as well as narrow molecular weight distributions (PDI < 2 for all polymers). Influences of the metals and comonomer feed content on the polymerization activity as well as on the incorporation rates (20.9–42.6%) were investigated. The achieved NB/NB‐COOCH3 copolymers were confirmed to be noncrystalline, exhibited good thermal stability (Td > 400°C) and showed good solubility in common organic solvents. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
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Rong Luo Ying Chen Ayusman Sen 《Journal of polymer science. Part A, Polymer chemistry》2008,46(16):5499-5505
The first copolymerization of acrylate and methacrylate with nonpolar 1‐alkenes in the presence of Brønsted acids as complexation agents has been reported. The addition of both homogeneous and heterogeneous Brønsted acids resulted in increased monomer conversion and 1‐alkene incorporation. Further, the heterogeneous Brønsted acids can be recycled without loss of activity. A direct correlation exists between the ability of the Lewis or Brønsted acid to bind to the ester group of the acrylate/methacrylate monomer and its ability to promote the copolymerization reaction. For Lewis acids, there is also a direct correlation between the charge/size ratio at the metal center and their ability to promote copolymerizations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5499–5505, 2008 相似文献
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Marzena Białek Ozanna Liboska 《Journal of polymer science. Part A, Polymer chemistry》2010,48(2):471-478
Immobilization of 1,2‐cyclohexylenebis(5‐chlorosalicylideneiminato)vanadium dichloride on the magnesium support obtained in the reaction of MgCl2·3.4EtOH with Et2AlCl gives a highly active precursor for ethylene homopolymerization and its copolymerization with 1‐octene. This catalyst exhibits the highest activity in conjunction with MAO, but it is also highly active with AlMe3 as a cocatalyst. On the other hand, when combined with chlorinated alkylaluminum compounds, Et2AlCl and EtAlCl2, it gives traces of polyethylene. Moreover, its catalytic activity is strongly affected by the reaction temperature: it increased with rising polymerization temperature from 20 °C to 60 °C. The kinetic curves obtained for the supported vanadium catalyst, in contrast to its titanium analogue, are of decay type, yet the reduction in the polymerization rate is rather moderate in the early stages of polymerization, and then it is relatively very slow. The vanadium catalyst gives copolymers at a lower yield than the titanium one does, but with the significantly higher 1‐octene content. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 471–478, 2010 相似文献
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Xianhui Zhang Guangqian Zhu Qaiser Mahmood Mengmeng Zhao Liang Wang Chuyang Jing Xiaowu Wang Qinggang Wang 《Journal of polymer science. Part A, Polymer chemistry》2019,57(7):767-775
A stereoselectivity switchable polymerization of isoprene has been developed, which is catalyzed by iminoimidazole‐Co(II) and ‐Fe(II) complexes. The influence of substituents ranging from electron donating to the electron withdrawing on the iminoimidazole‐Co(II) and ‐Fe(II) catalysts is investigated for isoprene polymerization. Two sets of iminoimidazole‐Co(II) and ‐Fe(II) complexes have been prepared and fully characterized. X‐ray crystallography analysis reveals that the complexes Co1 and Fe1 adopt distorted tetrahedral geometries. In the presence of AlEt2Cl as co‐catalyst, all the Co(II) complexes are active and the catalytic activity is highly dependent on the molar ratio of Al/Co. All the Co(II) complexes exhibit higher activities at low Al/Co ratio. Compared with the Co(II) complexes, the Fe(II) complexes are essentially inactive under the identical condition. However, on activation with combination of AlEtCl2 and [Ph3C][B(C6F5)4], both Co(II) and Fe(II) complexes display high activities with good conversions of isoprene (up to >99%). Additionally, low molecular weight and high trans‐1,4‐unit (>96%) selectivity are characteristics of the resultant polyisoprene. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 767–775 相似文献
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Sen‐Wang Zhang Ling‐Pan Lu Ying‐Yun Long Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2013,51(24):5298-5306
A series of novel vanadium(III) complexes bearing bidentate phenoxy‐phosphine oxide [O,P=O] ligands, (2‐R1‐4‐R2‐6‐Ph2P=O‐C6H2O)VCl2(THF)2 ( 2a : R1 = R2 = H; 2b : R1 = F, R2 = H; 2c : R1 = tBu, R2 = H; 2d : R1 = Ph, R2 = H; 2e : R1 = R2 = Me; 2f : R1 = R2 = tBu; 2g : R1 = R2 = CMe2Ph) have been synthesized by adding 1 equiv of the ligand to VCl3(THF)3 dropwise in the presence of excess triethylamine. Under the same conditions, the adding of VCl3(THF)3 to 2.0 equiv of the ligand afforded vanadium(III) complexes bearing two [O,P=O] ligands ( 3c , 3f ). All the complexes were characterized by FTIR and mass spectra as well as elemental analysis. Structures of complexes 2c and 3c were further confirmed by X‐ray crystallographic analysis. On activation with Et2AlCl and ethyl trichloroacetate, these complexes displayed high catalytic activities for ethylene polymerization (up to 26.4 kg PE/mmolV·h·bar) even at high reaction temperature (70 °C) indicative of high thermal stability, and produced high molecular weight polymers with unimodal molecular weight distributions. Additionally, the complexes with optimized structure exhibited high catalytic activities for ethylene/1‐hexene copolymerization. Catalytic activity, comonomer incorporation, and polymer molecular weight can be controlled in a wide range via the variation of catalyst structure and the reaction parameters such as Al/V molar ratio, comonomer feed concentration, and reaction temperature. The monomer reactivity ratios rE and rH were determined according to 13C NMR spectra, which indicated these complexes preferred ethylene to 1‐hexene in the copolymerization. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5298–5306 相似文献
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Pérez CM Rodríguez-Delgado A Palma P Álvarez E Gutiérrez-Puebla E Cámpora J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13834-13842
Manganese alkyl complexes stabilised by 2,6-bis(N,N'-2,6-diisopropyl-phenyl)acetaldiminopyridine ((iPr)BIP) have been selectively prepared by reacting suitable alkylmanganese(II) precursors, such as homoleptic dialkyls [(MnR(2))(n)] or the corresponding THF adducts [{MnR(2)(thf)}(2)] with the mentioned ligand. For R=CH(2)CMe(2)Ph or CH(2)Ph, formally Mn(I) derivatives are produced, in which one of the two R groups migrates to the 4-position of the central pyridine ring in the (iPr)BIP ligand. In contrast, a true dialkyl complex [MnR(2)((iPr)BIP)] can be isolated for R=CH(2)SiMe(3). In solution, this compound slowly evolves to the corresponding Mn(I) monoalkyl derivative. A detailed study of this reaction provides insights on its mechanism, showing that it proceeds through successive alkyl migrations, followed by spontaneous dehydrogenation. Protonation of [Mn(CH(2)SiMe(3))(2)((iPr)BIP)] with the pyridinium salt [H(Py)(2)][BAr'(4)] (Ar'=3,5-C(6)H(3)(CF(3))(2)) leads to the cationic species [Mn(CH(2)SiMe(3))(Py)((iPr)BIP)](+). Alternatively, the same complex can be produced by reaction of the pyridine complex [{Mn(CH(2)SiMe(3))(2)(Py)}(2)] with the protonated ligand salt [H(iPr)BIP](+)[BAr'(4)](-). This last reaction allows the synthesis of analogous cationic alkylmanganese(II) derivatives, when precursors of type [MnR(2)((iPr)BIP)] are not available. Treatment of these neutral and cationic (iPr)BIP alkylmanganese derivatives with a range of typical co-catalysts (modified methylaluminoxane (MMAO), B(C(6)F(5))(3), trimethyl or triisobutylaluminum) does not lead to active ethylene polymerisation catalysts. 相似文献
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Li‐Ming Tang Yan‐Guo Li Wei‐Ping Ye Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2006,44(20):5846-5854
Ethylene–propylene copolymerization, using [(Ph)NC(R2)CHC(R1)O]2TiCl2 (R1 = CF3, Ph, or t‐Bu; R2 = CH3 or CF3) titanium complexes activated with modified methylaluminoxane as a cocatalyst, was investigated. High‐molecular‐weight ethylene–propylene copolymers with relatively narrow molecular weight distributions and a broad range of chemical compositions were obtained. Substituents R1 and R2 influenced the copolymerization behavior, including the copolymerization activity, methylene sequence distribution, molecular weight, and polydispersity. With small steric hindrance at R1 and R2, one complex (R1 = CF3; R2 = CH3) displayed high catalytic activity and produced copolymers with high propylene incorporation but low molecular weight. The microstructures of the copolymers were analyzed with 13C NMR to determine the methylene sequence distribution and number‐average sequence lengths of uninterrupted methylene carbons. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5846–5854, 2006 相似文献
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Toru Doi Akira Akimoto Akikazu Matsumoto Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1996,34(3):367-373
Radical copolymerization of N-methylmaleimide (MeMI) as well as other N-alkylmaleimides (RMI) and isobutene (IB) was carried out with 2,2′-azobis(isobutyronitrile) as an initiator at 60°C. The initial rate of the copolymerization (Rp) was dependent on the monomer composition and was maximum at the 40 mol % of MeMI in the feed. A solvent effect on the Rp and the monomer reactivity ratio was observed in this copolymerization system, i.e., copolymerization in chloroform produced a higher Rp and an alternating tendency compared with those in dioxane (rMeMI = 0.14, r1B = 0 in chloroform and rMeMI = 0.47, r1B = 0 in dioxane). The alternating copolymer of RMI and IB shows a high glass transition temperature (Tg) and excellent thermal stability, e.g., the Tg and the thermal decomposition temperature (Td) were 152 and 363°C, respectively, for the alternating copolymer of MeMI and IB. Both the Tg and Td increased as the concentration of the MeMI unit in the copolymers increased. Colorless transparent sheets were obtained from press molding the alternating copolymers. They showed excellent mechanical and optical properties. © 1996 John Wiley & Sons, Inc. 相似文献
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Hiroshi Sugimoto Hiromitsu Ohshima Shohei Inoue 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3549-3555
The first successful example of the formation of polycarbonate from 1-atm carbon dioxide and epoxide was demonstrated by the alternating copolymerization of carbon dioxide and epoxide with manganese porphyrin as a catalyst. The copolymerization of carbon dioxide and cyclohexene oxide with (porphinato)manganese acetate proceeded under the 1-atm pressure of carbon dioxide to give a copolymer with an alternating sequence. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3549–3555, 2003 相似文献