Olefin polymerization copolymers

Keywords Catalyzed olefin polymerization, Chain shuttling catalysis, Chain transfer, Olefin block copolymers, Thermoplastic elastomers... 

Despite the potentially stoichiometric nature of the reaction with the CSA, a similar calculation of the number of chains per catalyst molecule reveals that the polymerization is highly catalytic in the hafnium and zirconium species. The chain shuttling methodology is capable of generating unlimited olefin block copolymer chains per catalyst. For example, the synthesis of sample 6 results in formation of -260 chains per total catalyst ... 

The production of olefin block copolymers has been an aspiration of academic researchers and polymer manufacturers alike. Tremendous progress toward this end has been achieved in recent years with the discovery of several designer catalysts capable of living olefin polymerization. However, the stoichiometric nature of the living process, coupled with related process limitations of low polymerization temperatures and slow batch processes, have precluded these approaches from widespread application. 

Well developed is the anionic polymerization for the preparation of olefin/di-olefin - block copolymers using the techniques of living polymerization (see Sect. 3.2.1.2). One route makes use of the different reactivities of the two monomers in anionic polymerization with butyllithium as initiator. Thus, when butyl-lithium is added to a mixture of butadiene and styrene, the butadiene is first polymerized almost completely. After its consumption stryrene adds on to the living chain ends, which can be recognized by a color change from almost colorless to yellow to brown (depending on the initiator concentration). Thus, after the styrene has been used up and the chains are finally terminated, one obtains a two-block copolymer of butadiene and styrene ... 

The chemical industry manufacturers a large variety of semiciystalline ethylene copolymers containing small amounts of or-olefins. These copolymers are produced in catalytic polymerization reactions and have densities lower than those of ethylene homopolymers known as high density polyethylene (HDPE). Ethylene copolymers produced in catalytic polymerization reactions are usually described as linear ethylene polymers, to distinguish them from ethylene polymers containing long branches which are produced in radical polymerization reactions at high pressures. 

The preparation of PnBA-g-PE and PtBA-g-PE graft copolymers was reported using Fe-mediated olefin polymerization, chain shuttling with Zn and ATRP techniques [108]. Terminally hydroxyl PE was synthesized from Zn-terminated PE by oxidation and hydrolysis, as referred to above. It was converted to methacrylated PE, as PE macromonomer, using methacryloyl chloride. The resulting PE macromonomer was used for the copolymerization of nBA or tBA by ATRP using CuBr/tris((N,N-dimclhylamino)clhyl)aminc. The obtained graft copolymers were characterized by GPC, DSC, and JH NMR. 

Solid-Catalyzed Olefin Polymerization. A third area where extremely challenging polymerization reaction engineering problems arise is in transition-metal catalyzed polymerization of olefins such as ethylene, propylene and their copolymers. 

Switching from olefin metathesis to Ziegler Natta polymerization is of interest in order to prepare block copolymers and to establish the relationship between these two related modes of olefin polymerization. Model studies for this purpose included the conversion of titancyclobutanes 10 and 7a into titanium alkyl compounds Eq. (30a and b) by the addition of 1 equivalent of ethanol [43],... 

M. Zintl, and B. Rieger, Novel Olefin Block Copolymers through Chain-Shuttling Polymerization, Angew. Chem. Int. Ed. 46, 333-335 (2007). 

Insite Not a process, but a range of constrained-geometry metallocene catalysts for polymerizing olefins. Olefin block copolymers made using these catalysts have the trade name Infuse. Developed by J.C. Stevens at the Dow Chemical Company, for which he received several medals. 

Polymers with even narrower mass distributions, e.g. with PDI values close to 1, arise in living polymerization systems, in which no chain termination processes can occur at all, such that all chains remain bound to the metal centre from which they have started to grow at the same time. Living polymerizations, which offer useful opportunities, e.g. with regard to the production of block copolymers by exchange of one monomer for another, occur in anionic polymerizations of styrenes or butadienes such as are induced by simple lithium alkyls. For a-olefin polymerization catalysts of the type discussed above, living polymerizations are rare. These more elaborate catalysts can thus release a newly formed polymer chain within a time interval of typically less than one... 

Xu, G. Chung, T.C. Borane chain transfer agent in metallocene-mediated olefin polymerization synthesis of borane-terminated polyethylene and diblock copolymers containing polyethylene and polar polymer. J. Am. Chem. Soc. 1999,121, 6763. 

Kashiwa, N. Fukui, K. Process for production of 4-methyl-1-pentene polymer or copolymer. US Patent 4,659,792, December 23, 1985 Kaminsky, W. The discovery of metallocene catalysts and their present state of the art. J. Polym. Sci. Part A Polym. Chem. 2004, 42, 3911-3921. Hlatky, G.G. Heterogeneous single-site catalysts for olefin polymerization. Chem. Rev. 2000, 100, 1347-1376. 

As previously mentioned, the properties of olefm-CO copolymers depend strongly on the nature of the olefin employed. The glass transition temperature of 1-olefin-CO copolymers decreases from room temperature to nearly -60 °C upon increasing the chain length of the 1-olefin from propylene to 1-dodecene [33]. By contrast to polar ethylene-CO copolymers, copolymers with higher l-olefins display a hydrophobic character. For 1-olefin copolymerization, catalysts with entirely alkyl-substituted diphosphine hgands R2P-(CH2) -PR2 (R=alkyl, by comparison to R=Ph in dppp) such as 3 are particularly well-suited [48]. Efhylene-l-olefin-CO terpolymers and 1-olefin-CO copolymers can be prepared in aqueous polymerizations [43, 47, 48]. In the aforementioned copolymerization reactions, the polyketone was reported to precipitate during the reaction as a sohd [45, 47, 48, 50]. However, in the presence of an emulsifier such as sodium dodecyl sulfate (SDS) and under otherwise suitable conditions, stable polymer latexes can be obtained. 

Mn 2 to 4). In olefin polymerization as well as CO copolymerization, a Umited conversion of liquid 1-olefin (co)monomers is yet to be overcome in many cases. As an example of properties that could find potential appUcation, polyolefins contain a negligible proportion of double bonds by comparison to styrene-butadiene copolymers, a hydrocarbon polymer currently prepared by free-radical emulsion polymerization on a large scale. This can result in a considerably higher stability towards UV-Ught and air of polymer films formed from polyolefin latexes. 

Since the discovery of olefin polymerization using the Ziegler-Natta eatalyst, polyolefin has become one of the most important polymers produeed industrially. In particular, polyethylene, polypropylene and ethylene-propylene copolymers have been widely used as commercial products. High resolution solution NMR has become the most powerful analytieal method used to investigate the microstructures of these polymers. It is well known that the tacticity and comonomer sequence distribution are important factors for determining the mechanical properties of these copolymers. Furthermore, information on polymer microstructures from the analysis of solution NMR has added to an understanding of the mechanism of polymerization. 

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