Copolymerization ethene-styrene

Another aspect of interest related to the terpolymerization with the P N systems is the relative rate of the copolymerization of styrene and ethene. The aromatic olefin copolymerizes more rapidly than ethene, but, much more ethene is inserted in the terpolymerization experiment. Therefore, the synthesis of terpolymers with high styrene content using... 

Sernetz, F. G. Mulhaupt, R. Fokken, S. Okuda, J. Copolymerization of ethene with styrene using methylalumi-noxane-activated bis(phenolate) complexes. Macromolecules 1997, 30, 1562-1569. 

Cationic polymerization is applied almost exclusively to monomers with olefinic double bonds. Susceptible are double bonds whose carbon atoms carry electron-donating substituents such as alkyl groups. Thus, isobutene with two methyl groups adjacent to the double bond polymerizes readily, propene with only one is sluggish, and ethene with none is inert a-methyl styrene is more reactive than styrene vinyl ethers are reactive, but vinyl chloride is not. The most important commercial product is butyl rubber, produced by copolymerization of isobutene with small amounts of isoprene, initiated by A1C13, BF3, or TiCl4 [82]. 

As a consequence of the living nature of the copolymerization wifh fhis catalyst, palladium-capped block copolymers of norbornene and ethene as well as of norbornene, ethene, and styrene were synthesized [61]. Higher activities (up to ten times higher) were observed for a series of oxazohne-phosphine complexes (e.g., 31). Several complexes, modified with bisphosphine monooxide and monosulfide ligands (Scheme 8.8, 32 and 33), were also used as catalysts precursors. The best reported turnover frequency is 0.6x10 mol (molh) at 80°C [62, 63]. A slightly lower activity was observed for fhe ketophosphine containing catalyst precursor 34 [64]. The activity of catalyst precursors 35, 36, and 37 is even lower [65]. 

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. 

Daniello, C., Decandia, F., Oliva, L. and Vittoria, V. (1995) Correlation between microstructure and physical-properties in styrene ethylene copolymers. Journal of Applied Polymer Science 58, 1701-1706. Sernetz, F.G., Mulhaupt, R., Fokken, S. and Okuda, J. (1997) Copolymerization of ethene with styrene using methylaluminoxane-activated bis(phenolate) complexes. Macromolecules 30, 1562-1569. 

Aeby, A. Consiglio, G Ethene and styrene insertion into the Pd-acyl bond of [Pd(COMe)(P N) (solv)]03SCp3 and its role in the copolymerization of olefins with carbon monoxide. J. Chem. Soc., Dalton Trans. 1999, 655-656. 

The copolymerization of ethene and styrene is possible by single site catalysts such as metallocenes and amido (see structure (33)) [222,223]. Amounts of more than 50mol% of styrene could be incorporated into the copolymer. In dependence of the styrene content the copolymers show elastic to stiflF properties. The polymerization happens by both 1,2- and 2,1-insertion of the styrene unit the regioselectivity is low. 

When a-olefins such as propene and styrene are used in place of ethene or norbornene for this copolymerization, regio- and enantio-selectivities of the olefin insertion arise and the control of these becomes a difficult aspect for obtaining stereo-regular polyketones. In the head-to-tail copolymer, a chirotopic center exists per monomer unit. If the same enantioface of each a-olefin is selected by a catalyst, the resulting copolymer is isotactic in which all the chirotopic carbons in a polymer backbone possess the same absolute configuration. Thus, asymmetric copolymerization using a chiral catalyst is now attracting much attention. 

Beside these basic reactions with ethene and propene, numerous other monomers can be employed in the co- and terpolymeriza-tions with CO. Due to the huge number of publications, the reader is referred to literature for more information. For example, copolymerization with norbomene, norbomene derivatives, and styrene as well as functionalized monomers such as alcohols, carbonic adds, carbamates, amides, or epoxides is possible. Functionalities are usually required to be separated from the olefin by an alkyl spacer. ... 

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