| abstract |
The present invention relates to compositions and processes of making polymers having a controlled molecular weight distribution. The molecular weight distribution is controlled, for example, by controlling the relative monomer concentrations during contact with a pre-catalyst and/or using a catalyst comprising a catalytic amount of a molecule having the structure: wherein M = group 2 - 8 metal, preferably group 4 as a neutral or charged moiety; Y = any substituent including fused rings; L = any ligating group, especially a pyridyl or pyridylamide; X = alkyl, aryl, substituted alkyl, H or hydride, halide, or other anionic moiety; y = an integer from 0 to the complete valence of M; R = alkyl, aryl, haloalkyl, haloaryl, hydrogen, etc; x = 1 - 6, especially 2; Dashed line = optional bond, especially a weak bond; and X and (CR2)X may be tethered or part of a ring. |