Branch distribution incorporation efficiency

Incorporation efficiency can vary from one catalyst to another, and it can also vary among the active sites on the same catalyst. This natural variety of sites means that Phillips catalysts produce a characteristic distribution of branching within the MW distribution. This characteristic of the polymers results because sites that produce lower MW also incorporate... 

The homopolymers of 10 were branched and exhibited broad GPC molecular weight distributions. Studies of the homopolymers molecular weights from polymerization at different monomer concentrations while (1) holding the [10]/[I] ratio constant, and (2) employing different [10]/[I] ratios confirmed that major differences existed in homopolymerizations of 10 versus vinylferrocene.56 In ethylacetate the rate law was r = k [M]1 [I]0 5. Polymerizations in benzene exhibited low initiator efficiencies. The rate was three halves order in the concentration of 10, similar to that found for 8.53 Polymers incorporating 10 were able to catalyze the selective 1,4-hydrogenation of methyl sorbate, but not terminal or internal olefins.56 This resembled the catalytic behavior of styrene/r 6-(styrene)tricarbonylchromium copolymers in hydrogenation.75... 

The amount of in situ branching produced is a sensitive function of many variables. Catalyst and reaction parameters have a major influence on the following (a) the a-olefin generation relative to polymer formation, (b) 1-hexene generation relative to that of other linear a-olefins, (c) how sharp or flat the Schulz-Flory distribution of linear a-olefins is, and (d) how efficiently the a-olefins are incorporated as branches. 

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