Copolymers metallocene-catalyzed

Replacement of EPM copolymers and EPDM ter-polymers by saturated metallocene-catalyzed EO copolymer... 

Advances in Polymer Technology 22, No.3, FaU 2003, p.209-17 BINARY BLENDS OF EVA AND METALLOCENE-CATALYZED ETHYLENE-ALPHA-OLEFIN COPOLYMERS AND THEIR... 

Metallocene catalyzed ethylene copolymers (MCP) (8) Miranol Rhodia Inc. 

It was also reported that terminally borane-containing POs is available as another macroinitiator to prepare block copolymers (Fig. 4). These polymers were prepared by (1) the metallocene-catalyzed (co)polymerization of olefin(s) with organoborane compounds, for example, 9-borabicyclononane (9-BBN), as chain transfer agents [32], or by (2) the hydroboration of terminally unsaturated polyolefins with BBN [33-36]. 

The synthetic procedure of PE-fo-PCL using hydroxyl terminated polyethylene was reported [39]. Terminally hydroxylated polyethylene was prepared during a metallocene-catalyzed polymerization using controlled chain transfer reaction with alkylaluminum compounds. PE-fo-PCL block copolymer was synthesized from terminally hydroxylated PE and e-caprolactone (e-CL) using Sn(Oct)2 as a catalyst for ring opening polymerization. 

Block copolymers can be produced from terminally borane-containing polyolefins. These borane-containing POs can be synthesized by the metallocene-catalyzed (co)polymerization of olefin(s) monomer with 9-BBN as a chain transfer agent or by the metallocene catalyzed copolymerization of olefins with allyl-9-BBN [55,56], as referred to above. Alternatively, borane-containing POs were prepared by hydroboration of terminally unsaturated PO, for instance, terminally vinyl PE and terminally vinylidene PP [33-35,57]. Such method could produce diblock copolymers, such as polyethylene-block-poly(methyl methacrylate) (PE-fo-PMMA), polypropylene-foZock-poly(methyl methacrylate) (PP-fc-PMMA), polypropylene-foZock-poly(butyl methacrylate) (PP-fc-PBMA), and PP-fc-PS. 

PE graft copolymers were synthesized from PE-OH by Inoue et al. using ATRP techniques, adopting similar techniques as mentioned above [74]. PE-g-PMMA and Polyclhylcnc-gra/f-poly( -bulyl acrylate) (PE-g-PnBA) were prepared through the combination of metallocene-catalyzed ethylene/10-undecen-l-ol copolymerization and conversion of the copolymer into P E-g-Br, as a macroinitiator, for ATRP. Well-defined graft copolymers, PE-g-PMMA and PE-g-PnBA, were confirmed by analyses of the detached side chains. Resulting PE-g-PMMA worked well as a compatibilizer. 

Luo, Y.J., Baldamus, J., and Hou, Z.M. (2004) Scanditrm Ualf-metallocene-catalyzed syndiospecific styrene polymerization and styrene-etUylene copolymerization unprecedented incorporation of syndiotactic styrene-styrene sequences in styrene-etUylene copolymers. Journal of the American Chemical Society, 126, 13910. 

A combination of metallocene-catalyzed syndiospe-cific styrene polymerization and the metal-catalyzed radical polymerization affords various graft copolymers consisting of syndiotactic polystyrene main chains (G-8).433 The reactive C—Br bonds (7—22% content) were generated by bromination of the polystyrene main chain with AZ-bromos uccimid e in the presence of AIBN. 

Metallocene catalysis is an alternative to the traditional Ziegler-Natta vanadium-based catalysis for commercial polyolefin production, e.g. the use of metallocene-catalyzed ethylene alpha-olefin copolymers as viscosity index modifiers for lubricating oil compositions [23]. The catalyst is an activated metallocene transition metal, usually Ti, Zr or Hf, attached to one or two cyclopentadienyl rings and typically activated by methylaluminoxane. Metallocene catalysis achieves more stereo-regularity and also enables incorporation of higher alpha-olefins and/or other monomers into the polymer backbone. In addition, the low catalyst concentration does not require a cleanup step to remove ash. 

The first reactor-type thermoplastic polyolefin (R-TPO) was LLDPE/PP [Yamazaki and Eujimaki, 1970, 1972]. The three-component R-TPO s (PE with PP and EPR) soon followed [Strametz et al, 1975]. PE was also polymerized in the presence of active catalyst and an olefinic copolymer [Morita and Kashiwa, 1981]. Blending amorphous co-polyolefins with crystalline PO s (HDPE, LLDPE, PP), and a filler resulted in moldable blends, characterized by excellent sets of properties [Davis and Valaitis, 1993, 1994]. Blends of polycycloolefin (PCO) with a block copolymer (both polymerized in metallocene catalyzed process) and PE, were reported to show outstanding properties, viz. strength, modulus, heat resistance and toughness [Epple and Brekner, 1994]. 

PP resin structure and polymerization Usually, traditional PP random copolymers have lower haze values than homopolymers, though copolymers composed of phases having different refractive indices (i.e., heterophasic impact copolymers) cannot be clarified. Ziegler-Natta-catalyzed PP random copolymers usually have higher haze wilues than metallocene-catalyzed homopolymers that contain sorbitol-based clarifiers [10-10). 

Zheng, L., Farris, R.J. and Coughlin, E.B. (2001). Novel Polyolefin Nanocomposites Synthesis and Characterizations of Metallocene-Catalyzed Polyolefin Polyhedral Oligomeric Silsesquioxane Copolymers, Macromol, 34(23) 8034-8039. 

In case of the metallocene-catalyzed random copolymer of ethylene and alpha-olefin (POP and POE), incorporating more comonomer along the polymer backbone reduces density and crystallinity and hence, increases flexibility and softness. However, as the density is decreased, the melting point, crystallization peak temperature and heat resistance decrease and cycle times in injection molding increase. These deficiencies have limited the use of POEs in applications where heat resistance, high temperature compression set, and faster cycle times are desired. 

Block-Type Brushes by Sequential Polymerization The sequential hving polymerization of two macromonomers or a macromonomer with a conventional comonomer forms either block-block- or block-coil-type brush structures. For example, giant rod-coil amphiphilic block copolymer bmshes were prepared via a stepwise metallocene-catalyzed polymerization [58]. In the first step, a concentrated solution of methacryloyl end-functionalized PS macromonomer (DP = 18.3, MWD = 1.05) was polymerized by the organosamarium(iii) catalyst in THF. After PS macromonomer was completely consumed, the active center remained living, and tert-butyl methacrylate tert-butyl methacrylate (tBMA) as a comonomer was added to grow the second block. After termination by ethanol, the poly(tert-butyl methacrylate) (PtBMA) coil block was hydrolyzed into a hydrophihc block, poly(methacrylic acid) (PMAA). The final product consisted of a hydrophobic PS brush block and a hydrophihc PMAA coil. The hydrophilic PMAA coil collapsed in nonpolar solvents, which forced the block-coil CPBs to self-assembled into giant micelles with PMAA as the core component and the stiff PS brush block as the shell to stabihze the micelles. 

Zheng, L., Farris, R. J., and Goughlin, E. B. 2001. Novel polyolefin nanocomposites Synthesis and characterizations of metallocene-catalyzed polyolefin polyhedral oligomeric silsesquiox-ane copolymers. Macromolecules 34 8034-8039. 

These linear elastomers are produced by coordination polymerization using a Phillips or Z-N catalyst at low P and T. Here belongs Mxsten XLDPE from Eastman Chem. and Attane ULDPE from Dow. The first metallocene-catalyzed VLDPE was a hexene copolymer with p = 0.912 g mL made in the UNIPOL gas-phase process with Z-N catalyst and introduced by ExxonMobil as Exceed metallocene VLDPE. The resin has outstanding sealing properties (hot tack and seal strength) compared with ZN-VLDPE. The solution polymerization in a hydrocarbon usually is carried out in a continuously stirred tank reactor (CSTR), at r = 160-300 °C and P = 2.5-10 MPa with the residence time of 1-5 min [Dow in 1992 and UCC in... 

Toyota, A. Mizuno, A. Tsutsui, T. Kaneko, H. Kashiwa, N. Synthesis and characterization of metallocene-catalyzed propylene-ethylene copolymer with end-capped fnnctionahty. Polymer 2002, 43, 6351-6355. 

Matyjaszewski, K. Saget, J. Pyun, J. Schlogl, M. Rieger, B. Synthesis of polypropylene-poly(meth)acrylate block copolymers using metallocene catalyzed processes and snbseqnent atom transfer radical polymerization. J. Macromol. ScL, PureAppl. Chem. 2002, A39, 901-913. 

Bergstrom, C. H. Sperhch, B. R. Ruotoistenmaki, J. Seppala, J. V. Investigation of the microstructure of metallocene-catalyzed norbornene-ethylene copolymers using NMR spectroscopy. J. Polym. ScL, Part A.- Polym. Chem. 1998, 36, 1633-1638. 

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