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Poly(Ethene-co-Norbornene) Obtained with a Constrained Geometry Catalyst. A Study of Reaction Kinetics and Copolymer Properties (Articolo in rivista)

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Poly(Ethene-co-Norbornene) Obtained with a Constrained Geometry Catalyst. A Study of Reaction Kinetics and Copolymer Properties (Articolo in rivista) (literal)

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Thorshaug K. 1, Mendichi R. 2, Boggioni L. 3, Tritto I. 4, Trinkle S. 5, Friedrich C. 6, Mulhaupt R. 7 (2002)
Poly(Ethene-co-Norbornene) Obtained with a Constrained Geometry Catalyst. A Study of Reaction Kinetics and Copolymer Properties
in Macromolecules (Print); American Chemical Society, Washington (Stati Uniti d'America)
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Thorshaug K. 1, Mendichi R. 2, Boggioni L. 3, Tritto I. 4, Trinkle S. 5, Friedrich C. 6, Mulhaupt R. 7 (literal)

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Impact Factor = 3.697; Financial support from EC TMR Project Network N°ERB FMRX CT97-0116 GLASSCYCLICS (literal)

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Poly(ethene-co-norbornene) was synthesized using Me2Si(Me4Cp) (NtBu)TiCl2 activated with methylaluminoxane (MAO) as catalyst. As the molecular weight increases with time for up to one hour and very little chain transfer occurs, thus the copolymerization can be considered as quasi-living. Poly(ethene-co-norbornene) containing long-chain branches was obtained; the degree of branching decreased with an increasing norbornene molar fraction in the feed. The presence of long- chain branches was confirmed both by size exclusion chromatography and rheology; the branches were found evenly distributed in the copolymers. The relationship between the experimental conditions and the polymer architecture is discussed. (literal)

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1, 2, 3, 4 Istituto per lo Studio delle Macromolecole (CNR), via E. Bassini 15, I-20133 Milano, Italy. 5, 6, 7 Freiburger Materialforschungszentrum und Institut fur Makromolekulare Chemie der Albert-Ludwigs-Universitat, Stefan-Meier-Strasse 21, D-79104 Freiburg i.Br., Germany. (literal)

Titolo

Poly(Ethene-co-Norbornene) Obtained with a Constrained Geometry Catalyst. A Study of Reaction Kinetics and Copolymer Properties (literal)

Abstract

Poly(ethene-co-norbornene) was synthesized in toluene using Me2Si(Me4Cp) (NtBu)TiCl2 activated with methylaluminoxane (MAO) as catalyst. We found that at 50°C the molecular weight increases with time for up to one hour and very little chain transfer occurs, thus the copolymerization can be considered as quasi-living. The quasi-living nature requires high norbornene feed fractions; it is more pronounced at low temperatures and short reaction times. Mw / Mn = 1.3 (Mn = 100 kg / mol) was the lowest polydispersity index obtained when the copolymerization reaction was conducted at 50°C. Poly(ethene-co-norbornene) containing long-chain branches was obtained; the degree of branching decreased with an increasing norbornene molar fraction in the feed. The presence of long- chain branches was confirmed both by size exclusion chromatography and rheology; the branches were found evenly distributed in the copolymers. Rheology of poly(ethene-co-norbornene) was analyzed; the GN° minimum could be reached, most probably, because bulky bicyclic norbornene units inhibit crystallization. Compared to the literature data, the low level of long chain branches incorporated into our poly(ethene-co-norbornene) samples does not significantly affect the glass transition temperature. The relationship between the experimental conditions and the polymer architecture is discussed based on the proposed reaction scheme. (literal)

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