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Ethylene Units (ethylene + unit)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Isolated Ethylene Units in Isotactic Polystyrene Chain: Stereocontrol of an Isospecific Post-Metallocene Titanium Catalyst

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2004
Carmine Capacchione
Abstract Summary: Copolymerization of styrene with small amounts of ethylene using the catalyst system dichloro{1,4-dithiabutanediyl-2,2,-bis(4,6-di- tert -butyl-phenoxy)}titanium/methylaluminoxane results in the unprecedented formation of isotactic polystyrene containing isolated ethylene units. 13C NMR spectroscopic analysis of the copolymer indicates that an "enantiomorphic site" control mechanism for isospecific propagation is operating. DSC measurements also indicate the presence of isolated ethylene units which modify the crystallization behavior of the isotactic polystyrene. Schematic representation of the copolymerization of styrene with small amounts of ethylene using dichloro{1,4-dithiabutanediyl-2,2,-bis(4,6-di-tert-butyl-phenoxy)}titanium/methylaluminoxane as catalyst system. [source]

Molecular Dynamics of Podand Studied by Broadband Dielectric and Nuclear Magnetic Resonance Spectroscopies,,

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19-20 2007
Bakyt Orozbaev
Abstract Nuclear magnetic resonance (NMR) and broadband dielectric spectroscopies (BDS) were used to analyze the molecular dynamics in P10.3H Podand. The temperature studies of NMR line and magnetic spin,lattice relaxation times accompanied by DS investigation enabled us to distinguish three main dynamical processes connected with the motions of the P10.3H Podand chains. In the low-temperature region the magnetic relaxation was associated with fast axial C3 rotation of methyl groups. Moreover, two other independent processes were observed and interpreted as (i) segmental motion of both oxyethylene and ethylene units, and (ii) the overall motion involved in the melting process. [source]

Isolated Ethylene Units in Isotactic Polystyrene Chain: Stereocontrol of an Isospecific Post-Metallocene Titanium Catalyst

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2004
Carmine Capacchione
Abstract Summary: Copolymerization of styrene with small amounts of ethylene using the catalyst system dichloro{1,4-dithiabutanediyl-2,2,-bis(4,6-di- tert -butyl-phenoxy)}titanium/methylaluminoxane results in the unprecedented formation of isotactic polystyrene containing isolated ethylene units. 13C NMR spectroscopic analysis of the copolymer indicates that an "enantiomorphic site" control mechanism for isospecific propagation is operating. DSC measurements also indicate the presence of isolated ethylene units which modify the crystallization behavior of the isotactic polystyrene. Schematic representation of the copolymerization of styrene with small amounts of ethylene using dichloro{1,4-dithiabutanediyl-2,2,-bis(4,6-di-tert-butyl-phenoxy)}titanium/methylaluminoxane as catalyst system. [source]

Silyl-Terminated Ethylene- co -Norbornene Copolymers by Organotitanium-Based Catalysts

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2009
Roberto Marconi
Abstract Ethylene (E) and norbornene (N) were copolymerized in the presence of PhSiH3 as chain-transfer agent with [Ti(,5:,1 -C5Me4SiMe2NBut)(,1 -Me)2] precatalyst combined with [Ph3C][B(C6F5)4]. The silane was introduced at chain-ends of E- co -N copolymers with concomitant reinitiation of the growing polymer chain. The concentrations of the silane and polymer molecular weight are inversely correlated. The characteristic signals of SiH2Ph chain-ends were observed by 1H NMR. The Si heteroatom is predominantly adjacent to ethylene units in E- co -N copolymers with high N content. [source]