Olefin copolymerization

Ethylene-1-butene copolymers, 20 180 Ethylene-1-olefin copolymerization, 26 525 Ethylene-acrylic elastomers, 10 696-703 commercial forms of, 10 697-698 dynamic mechanical properties of,... 

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. 

This section reviews copolymerization studies and aims to give an overview of research on ethylene-1-olefin copolymerization, the role of ligand substitution in copolymerization and the polymerization mechanisms involved. The copolymerization behavior of a group of siloxy-substituted complexes is discussed because they have the ability to be activated at low MAO ratios and some of them provide excellent comonomer respraise. 

Table 1 Ethylene and 1-olefin reactivity ratios (rg) for selected metallocenes in ethylene/1-olefin copolymerization...

Siloxy substitution at the 3-position of the indenyl ligand (17) was found to remarkably improve the 1-olefin copolymerization ability, whereas substitution at the 2-position (15) slightly reduced the copolymerization ability as compared to the unsubstituted 5. The reason for this was suggested to be mainly the increased coordination gap aperture of the 3-siloxy-substituted complexes. Table 1 summarizes the ethylene reactivity ratio data obtained for the siloxy-substituted complexes 15, 16, and 17 The large difference in the ethylene and comonomer reactivity ratio values, the product of which is much below unity, emphasizes the prevailing tendency of the catalysts to produce copolymers with isolated comonomer units. The reason for the 15 0% lower incorporation of 1-hexadecene than 1-hexene was explained by the higher steric bulk and lower rate of diffusion of the longer a-olefin. 

More than fifty olefin chemical reactions have been described [24-26]. The 1-olefins copolymerize with many monomers, including various olefins, vinyl esters, acrylic acid, acrylic acid esters, sulfur dioxide, and carbon monoxide [3, 27 29]. The principal industrial... 

In summary, the prediction that (E)-(Z) selectivity in the ethene/intemal olefins copolymerization with group 4 metallocenes can be achieved by using ligands of suitable symmetry has been proved. In particular, it has been shown that C2- and Os-symmetric metallocenes are able to copolymerize ethene with (Z)- and ( >butene, respectively. 

Water-soluble l,3-bis(di(hydroxyalkyl)phosphino)propane derivatives were thoroughly studied as components of Pd-catalysts for CO/ethene (or other a-olefins) copolymerization and for the terpolymerization of CO and ethene with various a-olefins in aqueous solution (Scheme 7.17) [59], The ligands with long hydroxyalkyl chains consistently gave catalysts with higher activity than sulfonated DPPP and this was even more expressed in copolymerization of CO with a-olefins other than ethene (e.g. propene or 1-hexene). Addition of anionic surfactants, such as dodecyl sulfate (potassium salt) resulted in about doubling the productivity of the CO/ethene copolymerization in a water/methanol (30/2) solvent (1.7 kg vs. 0.9 kg copolymer (g Pd)" h" under conditions of [59]) probably due to the concentration of the cationic Pd-catalyst at the interphase region or around the micelles which solubilize the reactants and products. Unfortunately under such conditions stable emulsions are formed which prevent the re-use... 

A key feature of these catalysts is the open nature of the active sites, which allows them to incorporate other olefins into polyethylene including styrene that is, these are efficient catalyst for olefin copolymerization. 

A key impetus in the study of these materials was the pursuit of catalytic CO/olefin copolymerization, reactivity to which 431-438 and 447 and their parent alkyls are entirely inert. Though 448 has been found to react with norbomadiene, affording the insertion product Tp PdC7H8C (O)p-Tol) (449), it does so slowly (>1 day). However, when the parent p-Tolyl complex 440 is simultaneously exposed to both CO and norbor-nadiene, catalytic copolymerization ensues, affording the polyketone within hours (Section IV.A).140 141... 

Gesattigte und ungesattigte Athylen-a-Olefin-Copolymere 4.3.1. Copolymere des Athylens mit a-Olefinen... 

Copolymerization Parameters for Ethylene/a-Olefin Copolymerization with Various Metallocene/MAO Catalysts 1... 

Tables 13 and 14 summarize the quantitative data concerning the copolymerizations of captodative olefins with comonomers other than styrene. From these data, it can be concluded that captodative olefins copolymerize easily with various comonomers.

Table 5. Copolymerization parameters for ethene/a-olefin copolymerization by using different metallocene/MAO catalysts...

Table 1. A comparison of Pd-catalyzed CO/olefin copolymerization and early-transition-metal-catalyzed olefin polymerization.

To enhance understanding of the CO-olefin copolymerization reaction catalyzed by nickel organometallic complexes (for the similar copolymerization reaction catalyzed by palladium compounds, see below), consider the carbon monoxide insertion reaction with nickel(II) compounds containing the bidentate P, O donor B ... 

Carbon monoxide insertions into palladium-alkyl or palladium-aryl bonds were extensively studied in connection with the palladium-catalyzed CO-olefin copolymerization process . 

LCB-PE (long chain branched polyethylene) is not accessible through simple ethyl-ene/a-olefin copolymerization. Therefore, a bifunctional bimetallic catalyst was developed, in which one active center oligomerizes ethene to long-chain a-olefins, while the other copolymerizes them with ethene. 

Early work at Mitsui Petrochemicals concentrated on copolymerization of the multicyclic olefin dimethano-octahydronaphthalene (DMON, structure II (Ri = R2=H) in Fig. 4.1), using soluble vanadium catalysts [4] that eventually led to the commercialization of Apcl polyolefins [5]. Later, the utility of metallocene catalysts for cyclic olefin copolymerization was recognized by both Mitsui and Hoechst [6]. This led to the joint development of the Topas line of polyolefins [7], now being marketed by Ticona. 

Scheme 8.19 Catalyst precursors used for carbon monoxide-strained olefin copolymerization.

Complexes [Mn(X)(Tp Bu ipr)] (X = Cl, Br, NO3) have been reported and described to possess good activity for ethylene polymerization and ethylene-R-olefin copolymerization. The [Mn(Cl)(Tp,Bu,pr)]/Al(iBu)3/[Ph3C][B(C6F5)4] system is also active toward propylene and gives isotactic polypropylene.113 Spectral properties and electronic structure of the four-coordinate high-spin... 

Copolymerization of Vinylene Carbonate with Some Halo-Substituted Olefins. Copolymerization experiments were conducted using trans-dichloro-ethylene, vinylidene chloride, and CTFE since these monomers have a structural relation to the inhibiting impurities discussed above. With frans-dichloro-ethylene, no polymerization occurred, and only oligomers of VCA with a molecular weight of 300 were formed. Like dichlorovinylene carbonate, trans-dichloroethylene acts as an inhibitor, probably through degradative chain transfer by abstraction of a chlorine atom. 

Each monomer addition step interconverts the two organometallic components. The poly(methyl methacrylate) (PMMA) obtained is predominantly syndio-tactic, although isotactic PMMA has been obtained by using chiral indenyl zirconocenes in combination with non-zirconocene Lewis acids. No reports of attempted ethylene or a-olefin copolymerizations have been described. 

Alexander KdppI was born in Vilseck, Germany, in 1970. He received his chemical education and his Ph.D. degree at the University of Bayreuth. His dissertation in the research group of Professor H. G. Alt dealt with new support materials for the immobilization of cocatalytically active alumoxanes and their application in ethylene homopolymerization and ethylene/a-olefin copolymerization. He is currently a chemist for BASF AG in Ludwigshafen, Germany. 

Processes of ethene/a-olefin copolymerization are of great practical importance. Copolymerization of ethene with small amounts of highest a-olefins (1-butene, 1 -hexene, 1 -octene) allows one to produce linear low density polyethylene (LLDPE), which is one of the most widely used large-scale polyolefin products. Polypropylene, modified with small amounts of ethene, exhibits higher impact strength compared to isotactic homopolypropylene. Copolymerization of propene with large amounts of ethene and terpolymerization of ethene/propene/diene result in amorphous elastomer materials (rubbers) [103]. 

One of the features of olefin copolymerization kinetics is the effect of comonomer on the rate of ethene or propene polymerization during ethene/a-olefin or propene/ a-olefin copolymerization, i.e., the so-called comonomer effect (CEF). The rate enhancement of ethene or propene polymerization in the presence of a comonomer is observed for conventional ZN catalysts [80, 113-123] and for homogeneous [124-133] and supported metallocenes [134—136] and post-metallocenes catalysts [137-140]. The increase in activity was remarked in the presence of such comonomers as propene, 2-methylpropene, 1-butene, 3-methylbutene,4-methylpentene-l, 1-hexene, l-octene,l-decene, cyclopentene, styrene, and dienes. 

For understanding the nature of the comonomer effect, it is also very important that the rate enhancement takes place in the sequential processes of homo- and copolymerization, i.e., when the ethene homopolymerization is carried out after the a-olefin homopolymerization or ethene/a-olefin copolymerization [122, 123] (Table 6). 

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