Coordination Polymerization in Water Affording Amorphous Polyethylenes

Cite This

Files in this item

Checksum: MD5:d84a159c50eef229a4ac348da916fe47

HELD, Anke, Stefan MECKING, 2000. Coordination Polymerization in Water Affording Amorphous Polyethylenes. In: Chemistry: A European Journal. 6(24), pp. 4623-4629

@article{Held2000Coord-9809, title={Coordination Polymerization in Water Affording Amorphous Polyethylenes}, year={2000}, number={24}, volume={6}, journal={Chemistry: A European Journal}, pages={4623--4629}, author={Held, Anke and Mecking, Stefan} }

<rdf:RDF xmlns:dcterms="" xmlns:dc="" xmlns:rdf="" xmlns:bibo="" xmlns:dspace="" xmlns:foaf="" xmlns:void="" xmlns:xsd="" > <rdf:Description rdf:about=""> <dc:contributor>Held, Anke</dc:contributor> <dcterms:available rdf:datatype="">2011-03-24T18:14:33Z</dcterms:available> <dc:rights>Attribution-NonCommercial-NoDerivs 2.0 Generic</dc:rights> <dc:creator>Held, Anke</dc:creator> <void:sparqlEndpoint rdf:resource="http://localhost/fuseki/dspace/sparql"/> <dc:creator>Mecking, Stefan</dc:creator> <dcterms:abstract xml:lang="eng">The coordination polymerization of ethylene in water as a reaction medium was studied. Rubbery amorphous branched polyethylene was obtained when a known cationic diiminesubstituted methyl complex was employed as a catalyst precursor. High rates of up to 900 TOhÿ1 (turnover frequency) were observed. In contrast to solution polymerization in an organic solvent, the rate of suspension polymerization in water increases greatly with ethylene pressure in the range up to 20 bar; this indicates control of the polymerization rate by the concentration of the olefin monomer at the catalytically active site. The effect and mode of mass transfer phenomena were studied. A high catalyst stability in the aqueous coordination polymerization was observed. It was found to be due to an "encapsulation" of the water-insoluble catalyst precursor in the hydrophobic amorphous polymer during the polymerization reaction, and this resulted in strongly restricted accessibility for the aqueous phase. Surprisingly, exposure of the water-stable catalyst precursor to ethylene monomer in solution in the presence of water resulted in immediate decomposition. Polymer microstructure, and thermal and mechanical properties were investigated. The different degree of branching, molecular weight, and corresponding macroscopic properties of the polymers obtained in water as a reaction medium versus solution polymerization in methylene chloride under the same conditions are due to the different phase behavior during polymerization (suspension vs. solution), as opposed to an effect of water on the catalytically active centers.</dcterms:abstract> <dc:format>application/pdf</dc:format> <dcterms:hasPart rdf:resource=""/> <bibo:uri rdf:resource=""/> <dc:contributor>Mecking, Stefan</dc:contributor> <dc:language>eng</dc:language> <dcterms:bibliographicCitation>First publ. in: Chemistry: A European Journal 6 (2000), 24, pp. 4623-4629</dcterms:bibliographicCitation> <dspace:isPartOfCollection rdf:resource=""/> <dcterms:rights rdf:resource=""/> <dcterms:isPartOf rdf:resource=""/> <dc:date rdf:datatype="">2011-03-24T18:14:33Z</dc:date> <dcterms:title>Coordination Polymerization in Water Affording Amorphous Polyethylenes</dcterms:title> <dspace:hasBitstream rdf:resource=""/> <dcterms:issued>2000</dcterms:issued> <foaf:homepage rdf:resource="http://localhost:8080/jspui"/> </rdf:Description> </rdf:RDF>

Downloads since Oct 1, 2014 (Information about access statistics)

2000_Chemistry_Eur_J_6_4623_Mecking.pdf 827

This item appears in the following Collection(s)

Attribution-NonCommercial-NoDerivs 2.0 Generic Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.0 Generic

Search KOPS


My Account