Copolymerization of Ethylene with tert-Butylethylene Using Nonbridged Half-Titanocene-Cocatalyst Systems

Effect of para-Substituents in Ethylene Copolymerizations with 1-Decene, 1-Dodecene, and with 2-Methyl-1-Pentene Using Phenoxide Modified Half-Titanocenes-MAO Catalyst Systems

Effect of para-substituents in the ethylene (E) copolymerization with 1-decene (DC), 1-dodecene (DD), and with 2-methyl-1-pentene (2M1P) using a series of Cp*TiCl2 (O-2,6-i Pr2 -4-R-C6 H2 ) [R=H (1), t Bu (2), Ph (3), CHPh2 (4), CPh3 (5), SiMe3 (6), SiEt3 (7), and newly prepared 4-t BuC6 H4 (8) and 3,5-Me2 C6 H3 (9)]-MAO catalyst systems has been studied. The activities in these copolymerization reactions were affected by the para-substituent, and the SiMe3 (6), SiEt3 (7) and 3,5-Me2 C6 H3 (9) analogues showed the higher activities at 50 °C in the E copolymerization reactions with DC (1.06-1.44×106  kg-polymer/mol-Ti⋅h), DD (1.04-1.88×106  kg-polymer/mol-Ti⋅h) than the others, whereas no significant differences were observed in the comonomer incorporations. Complexes 6 and 7 also showed the higher activities at 50 °C in the E/2M1P copolymerization, and the 2M1P incorporation was affected by the para-substituent and the polymerization temperature; complex 9 showed better 2M1P incorporation at 25 °C.

Copolymerisation of 1-alkenes with bulky oxygen-containing olefins for dual-stage functionalisation of polyolefins

Pd–Diimine complexes catalyse the copolymerisation of 1-alkenes with olefins having a bulky oxygen-containing substituents, such as cyclic acetal or bicycloorthoester groups, affording the copolymers containing the comonomer unit up to 34%.

Solution XANES and EXAFS analysis of active species of titanium, vanadium complex catalysts in ethylene polymerisation/dimerisation and syndiospecific styrene polymerisation

Mechanistic studies in homogeneous catalysis through the solution transition metal K Edge XANES (X-ray absorption near-edge structure) and EXAFS (Extended X-ray absorption fine structure) analysis for vanadium and titanium complex catalysts for ethylene polymerisation/dimerization, and syndiospecific styrene polymerisation, including interpretation of the XANES spectra, have been introduced. The core excitation spectra of the complexes based on the time-dependent density functional theory (TD-DFT) can be used to interpret the Ti and V K-edge features and to extract information on the electronic structure from the XANES spectra. Theoretical calculations and experimental XAS analysis should have great potential for analysing the active species.

Microstructure of Copolymers of Norbornene Based on Assignments of 13C NMR Spectra: Evolution of a Methodology

An overview of the methodologies to elucidate the microstructure of copolymers of ethylene and cyclic olefins through ¹³C Nuclear magnetic resonance (NMR) analysis is given. ¹³C NMR spectra of these copolymers are quite complex because of the presence of stereogenic carbons in the monomer unit and of the fact that chemical shifts of these copolymers do not obey straightforward additive rules. We illustrate how it is possible to assign ¹³C NMR spectra of cyclic olefin-based copolymers by selecting the proper tools, which include synthesis of copolymers with different comonomer content and by catalysts with different symmetries, the use of one- or two-dimensional NMR techniques. The consideration of conformational characteristics of copolymer chain, as well as the exploitation of all the peak areas of the spectra by accounting for the stoichoimetric requirements of the copolymer chain and the best fitting of a set of linear equation was obtained. The examples presented include the assignments of the complex spectra of poly(ethylene-co-norbornene (E-co-N), poly(propylene-co-norbornene (P-co-N) copolymers, poly(ethylene-co-4-Me-cyclohexane)s, poly(ethylene-co-1-Me-cyclopentane)s, and poly(E-ter-N-ter-1,4-hexadiene) and the elucidation of their microstructures.

Synthesis and structural analysis of aryloxo-modified trinuclear half-titanocenes, and their use as catalyst precursors for ethylene polymerisation

The synthesis and structural analysis of aryloxo-modified trinuclear half-titanocenes have been explored: the Cp* analogues showed higher activities for ethylene polymerisation than the related mononuclear analogues.

Half-titanocenes for precise olefin polymerisation: effects of ligand substituents and some mechanistic aspects

Selected examples concerning effects of both cyclopentadienyl fragment (Cp') and anionic donor ligand (Y) in nonbridged modified half-titanocenes of the type, Cp'TiX(2)(Y) (X = halogen, alkyl), as new type of olefin polymerisation catalysts have been reviewed. These complexes displayed unique characteristics not only for ethylene (co)polymerisation but also for syndiospecific styrene polymerisation, ethylene/styrene copolymerisation; precise fine tuning of the ligand substituents plays an important role for the successful (co)polymerisation; a different mechanistic consideration for the syndiospecific styrene polymerisation, which can explain the copolymerisation behaviour in this catalysis, has also been introduced.

Half-titanocenes containing anionic ancillary donor ligands as promising new catalysts for precise olefin polymerisation

Recent efforts concerning nonbridged half-titanocenes containing anionic donor ligand of the type, Cp'TiX(2)(Y) [Cp' = cyclopentadienyl group; X = halogen, alkyl; Y = anionic ancillary donor ligands such as aryloxo, ketimide etc.], as new types of olefin polymerisation catalysts have been reviewed. It has been demonstrated that these complexes displayed unique characteristics especially for ethylene copolymerisation affording new polymers by efficient incorporation of bulky olefins (so called "traditionally unreactive" monomers in transition metal catalysed coordination polymerisation), that have not been attained by the ordinary catalysts.