Copolymerizations of ethylene and α-olefins with supported piano-stool catalysts

Living Coordinative Chain-Transfer Polymerization and Copolymerization of Ethene, α-Olefins, and α,ω-Nonconjugated Dienes using Dialkylzinc as “Surrogate” Chain-Growth Sites

“…More specifically, the data in Table for copolymerizations of ethene with 1-hexene (runs 1 and 2) and with 1,5-HD (runs 6 and 7) confirm that, under identical conditions, M n values for the isolated copolymers are directly dependent on the molar equivalents of ZnEt 2 that are employed and with product yields once again remaining invariant. GPC of the copolymer products further revealed monomodal molecular weight distributions possessing slightly broader polydispersitiesan observation that may be indicative of slower reversible chain transfer relative to propagation. , Importantly, Figures and present structural analyses of the copolymers by 13 C{ 1 H} NMR (150 MHz) spectroscopy, and in each case, the comonomer is almost exclusively incorporated into the polymer backbone as isolated units and with only a trace of either consecutive comonomer dyads (e.g., H−H or HD−HD) or alternating comonomer triads (e.g., H−E−H or HD−E−HD) being observed. ,, It is also essential to point out that incorporation of 1,5-HD occurs exclusively by cyclopolymerization to produce isolated methylene-1,3-cyclopentane units. Finally, DSC analyses of all the copolymers of Table revealed phase transitions that are distinct from those expected for each of the possible homopolymers.…”

“Bound but Not Gagged”Immobilizing Single-Site α-Olefin Polymerization Catalysts

“…Wang and co-workers used Diels-Alder cross-linked polystyrene to encapsulate a metallocene/MAO catalyst system, 656 and Coughlin et al developed supported half-metallocene "piano stool" catalysts, covalently bound to poly(styrene-co-4-hydroxystyrene). 657 Section 11.6. Alt reviews self-immobilization 658 and related metallacyclic complexes.…”

Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

“…In the case of the catalytic system comprising a chlorophenoxy ligand the fraction obtained melted just two degrees lower than the homopolymer. This indicates the presence of a greater number of structural errors in the chain of the syndiotactic polystyrene (sPS) obtained as compared with the homopolymerization sPS [15].…”

“…LTiMe 2 Y, new MAO containing Y ligands and active catalytic cations CpTiMeY + as a product of LTiMe 2 Y decomposition with subsequent interaction with MAO, are these products [7,15].…”

“…LTiCl 2 (OC 6 H 4 X-p) complexes were prepared by the procedures described in the available literature [13][14][15][16].…”