The incorporation of 5‐vinyl‐2‐norbornene (VNB) into ethylene‐norbornene copolymer was investigated with catalysts [Ph2C(Fluo)(Cp)]ZrCl2 ( 1 ), rac‐[Et(Ind)2]ZrCl2 ( 2 ), and [Me2Si(Me4Cp)tBuN]TiCl2 ( 3 ) in the presence of MAO by terpolymerizing different amounts of 5‐vinyl‐2‐norbornene with constant amounts of ethylene and norbornene at 60°C. The highest cycloolefin incorporations and highest activity in terpolymerizations were achieved with 1 . The distribution of the monomers in the terpolymer chain was determined by NMR spectroscopy. As confirmed by XRD and DSC analysis, catalysts 1 and 3 produced amorphous terpolymer, whereas 2 yielded terpolymer with crystalline fragments of long ethylene sequences. When compared with poly‐(ethylene‐co‐norbornene), VNB increased both the glass transition temperatures and molar masses of terpolymers produced with the constrained geometry catalyst whereas decreased those for the metallocenes. 相似文献
Summary: Polypropylene-nanocomposites were prepared by in-situ polymerization with the catalysts systems rac[Et(IndH4)2]ZrCl2, Me2Si(Flu)(Ind)ZrCl2 and rac[Me2Si(2-Me-4-(1-Naph)Ind)2]ZrCl2. The type and size of the nanoparticles and the concentration of the propene were varied. The activity is independent of the type and the size of the filler. It was observed that the filler contents in the polypropylene-nanocomposites depend on the catalysts system used. The morphology results using TEM revealed that the nanoparticles are uniformly distributed in the isotactic polypropylene matrix. Additionally, the melting points, glass temperatures and crystallization temperatures changed with the amount of the fillers. 相似文献
Synthesis and characterization of a novel carbazole‐based monomer, 9‐(bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl)‐9H‐carbazole (BHMCZ) and its copolymerization with ethylene by using two metallocene/MAO catalyst systems are presented. The monomer was characterized by means of NMR spectroscopy, MS and elementary analysis. Copolymerization studies were conducted using [Ph2C(Ind)(Cp)ZrCl2] and [Ph2C(Flu)(Cp)ZrCl2] catalysts. The [Ph2C(Ind)(Cp)ZrCl2] catalyst gave a copolymer containing as much as 4.6 mol‐% of BHMCZ. Polymers were characterized using NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). 相似文献
Meso-[Me2Si(2-Me-4,6-iPr2Ind)2ZrCl2 was synthesized in a pure form and used as catalyst for the copolymerization of ethene and α-olefins. The results are compared with polymers obtained by C1-symmetric metallocenes and constrained geometry catalysts. The activity of the meso form is remarkable high and reaches more than 100000 kg polymer/mol Zr · h. The ligand structure has large influence on the incorporation of 1-octene forming thermoplastics (LLDPE) and thermoplastic elastomers (POE). 相似文献
Using two different zirconocene/MAO catalyst systems, propene was copolymerized with the comonomers 2‐(9‐decene‐1‐yl)‐1,3‐oxazoline and 2‐(4‐(10‐undecene‐1‐oxo)phenyl)‐1,3‐oxazoline, respectively. The catalysts used were rac‐Et[Ind]2ZrCl2 and rac‐Me2Si[2‐Me‐4, 5‐BenzInd]2ZrCl2. Up to 0.53 mol‐% oxazoline could be incorporated into polypropene. Oxazoline content, molecular weight, degree of isotacticity and melting behavior were dependent on the catalyst system, comonomer structure and comonomer concentration in the feed. 相似文献
The copolymerization of propene and norbornene with the isospecific metallocene catalyst dimethylsilylenebis(η5-inden-1-yl)zirconium dichloride/methylaluminoxane ((CH3)2Si[Ind]2ZrCl2/MAO) was investigated. Because of the surprisingly high reactivity of the cyclic olefin copolymers with a norbornene content of 11 mol-% up to 98 mol-% were synthesized. The resulting copolymers are amorphous. The glass transition temperatures studied by differential scanning calorimetry measurements increase with rising norbornene content in the copolymer. High glass transition temperatures of Tg > 240°C were found for the copolymers with the highest content of norbornene. 相似文献
Summary: The metallocenes rac‐C2H4(Ind)2ZrCl2 ( 1 ), rac‐Me2Si(Ind)2ZrCl2 ( 2 ), and rac‐Me2Si(2‐Me‐benz[e]Ind)2ZrCl2 ( 3 ) efficiently copolymerize propene and 5‐vinyl‐2‐norbornene (VNB). 1 and 2 give a high VNB content and high productivities, whereas 3 gives moderate incorporation. Surprisingly, precatalysts 1 and 2 , which have very closely related structures, showed very different reactivities toward VNB, with 1 having a greater affinity for VNB than for propene. The copolymers are quantitatively converted into polyolefins with polar functionalities.
Sterically hindered olefins like norbornene, dimethanooctahydronaphthalene (DMON), 4‐methylpentene, and 3‐methylbutene can be copolymerised with ethene by metallocene/MAO catalysts. Different C2‐, Cs‐ and C1‐symmetric and meso‐zirconocenes were used. Only isolated and alternating norbornene sequences but no norbornene blocks are formed by substituted [Me2C(Cp‐R)(Flu)]ZrCl2 catalysts. The alternating microstructure leads to melting points up to 270°C for ethene‐norbornene copolymers and up to 380°C for the semi‐crystalline alternating copolymer of ethene and DMON. Other sterically hindered olefins such as 3‐methylpentene build more blocky structures with high glass transition temperatures. The mechanism for the insertion reaction of the different catalysts is discussed. 相似文献
Dual-site ethene/1-hexene copolymerizations with MAO-activated (1,2,4-Me3Cp)2ZrCl2 and (Me5Cp)2ZrCl2 catalysts were performed. Copolymers with narrow molecular weight distributions and bimodal short chain branching distributions could be produced. The combined catalyst system demonstrates a number of discrepancies from an expected average behavior of the individual sites. Dual-site (1,2,4-Me3Cp)2ZrCl2/(Me5Cp)2ZrCl2 systems produce copolymers with lower incorporation than expected. Clear evidences for relative activity enhancement of the (Me5Cp)2ZrCl2 catalyst in the mixture were observed in melting endotherms and Crystaf profiles. Molecular weights obtained by the mixture were higher than for any of the individual catalysts. A similar effect is observed for a dual-site system of the (1,2,4-Me3Cp)2ZrCl2 catalyst together with the Me4Si2(Me4Cp)2ZrCl2 catalyst as an alternative to (Me5Cp)2ZrCl2. 相似文献
The main focus of this study is the ethylene/hexene copolymerization with the silica supported metallocene SiO2/MAO/rac‐Me2Si[2‐Me‐4‐Ph‐Ind]2ZrCl2. Polymerizations were carried out in toluene at a reaction temperature of 40°C–60°C and the cocatalyst used was triisobutylaluminium (TIBA). The kinetics of the copolymerization reactions (reactivity ratios rE/H, monomer consumption during reaction) were investigated and molecular weights Mw, molecular weight distributions MWD and melting points Tm were determined. A schematic model for the blend formation observed was developed that based on a filtration effect of monomers by the copolymer shell around the catalyst pellet. 相似文献
The copolymers of ethylene with 5-ethylidene-2-norbornene containing 10–65% of the cyclic comonomer have been prepared with the use of three ansa-metallocene catalysts, namely, Et[Ind]2ZrCl2-methylaluminoxane, Et[IndH4]2ZrCl2-methylaluminoxane, and Me2Si[Ind]2ZrCl2-methylaluminoxane. Side groups >C=CH-CH3 capable of participation in the ozonolysis reaction have been incorporated into polymer chains via the copolymerization of ethylene with the cyclic comonomer. As evidenced by DSC, and X-ray diffraction, and very cold neutron scattering measurements of the supramolecular structure of the copolymers, the enrichment of the copolymer with the cyclic comonomer causes transformation of the ethylene-5-ethylidene-2-norbornene copolymer from the semicrystalline state to the amorphous state. This effect is accompanied by an increase in the density and optical transparency of the material and a rise in its glass transition temperature. Among the copolymers under study, the highest Tg (83°C) is exhibited by the copolymer synthesized with the Et[Ind]2ZrCl2-methylaluminoxane catalyst and containing 30 mol % 5-ethylidene-2-norbornene. 相似文献
We investigated the ethylene copolymerization by utilizing Me2Si(Ind)2ZrCl2/MAO and Me2Si(Ind)2ZrCl2/MAO/SiO2 with 10-undecene-1-oxytrimethylsilane and 10-undecene-1-oxytriisopropylsilane and the ethylene copolymerization by using iPr(CpInd)ZrCl2/MAO and iPr(CpInd)ZrCl2/MAO/SiO2 with 5-norbornene-2-methyleneoxytrimethylsilane and 5-norbornene-2-methyleneoxytriisopropylsilane. The trimethylsilyl (TMS) protecting group could not prevent the catalyst deactivation caused by the addition of the polar comonomer. In contrast to that, good catalyst activities and comonomer contents were obtained with the triisopropylsilyl (TIPS) protected monomer. The homopolymerization of 10-undecene-1-OTIPS was carried out with Me2Si(Ind)2ZrCl2/MAO. 相似文献