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Nitroxyl radicals were used as functionalizing agents during the free radical postreactor modification process of polyolefins carried out in the melt. The 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (HO‐TEMPO) and the 4‐benzoyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (BzO‐TEMPO) free radicals were successfully grafted onto a polyethylene‐based material (ethylene‐co‐1‐octene copolymer) by coupling reaction with polymer macroradicals; these last were formed by H‐abstraction through peroxide addition. The macromolecular structure of the functionalized polyolefins was assessed by 1H‐NMR, FTIR spectroscopy, and SEC measurements which were used to evidence the grafting site, to evaluate the grafting level and to highlight the occurrence of chain extension through crosslinking side reactions. Indeed the use of proper model compounds allowed the preparation of accurate FTIR calibration curves for the quantitative determination of the functionalization degree. Besides the high temperature SEC analysis highlighted that this fast and simple coupling reaction between macroradicals and nitroxyl free radicals grants the grafting of functionalities onto the polyolefin backbone by contemporarily preventing the side reactions liable of the structure and MW modification of the pristine polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

No abstract

Essentially complete regioselectivity and good catalytic activity can be achieved in the copolymerization of propene with carbon monoxide using palladium-containing catalytic systems modified by the basic diphosphine ligand With (6,6'-dimethylbiphenyl-2,2'-diyl)bis(dicyclohexylphosphine) a stereoregular poly(l-oxo-2-methyltrimethylene) was obtained. When the optically pure ligand was used, the produced copolymer showed an intense band in the circular dichroism spectrum in the region around 275 nm as expected for a prevailingly isotactic structure. In most cases the copolymers can be isolated as a poly [spiro-2,5-(3-methyltetrahydrofuran)]. NMR analysis of the regioregular copolymers and comparison with model compounds suggest that the insertion of the propene units during the growth process takes place with primary regioselectivity.

With 1,3‐propanediylbis(diisopropylphosphine) as ligand L in [Pd(CF3CO2)2L] precatalysts, the strict alternating copolymerization of propylene with carbon monoxide can be carried out with complete regioselectivity and good stereoselectivity. Thus the first synthesis of a regular poly(1‐oxo‐2‐methyltrimethylene) has been achieved. The possible configurations in this polymer are shown below.