bis(imino) pyridyl iron complexes: the effect of polymerization conditions on activities and thermal behaviors of polyethylene

Two late transition metal catalysts based on 2,6‐bis(imino)pyridine iron(ii) were synthesized by introducingmethyl substitution (catalyst a) and t‐butyl substitution (catalyst b) at the ortho position of the aryl ringsof the ligand. comparative ethylene polymerizations using the catalysts showed quiet different behaviors.the activity of catalyst a was higher than that of catalyst b in all of the polymerization conditions used. thehighest activities of these catalysts were obtained at almost 25°c. activities of the catalysts increasedwith increasing both monomer pressure and [al]: [fe] molar ratio. multi modal peaks were appeared inthe dsc analysis of oligomers obtained by catalyst a, while in the dsc analysis of the polymer obtainedusing catalyst b unimodal peaks were appeared. it is suggested that catalyst a containing lessbulkier substitution produced polymer with different molecular weight fractions and differentmelting points. besides, the t‐butyl group in catalyst b resulted in producing polyethylene (pe) withsingle sharp dsc peaks; the latter is due to the formation of highly linear polyethylene. polymerizationtemperatures affected the pattern of dsc thermograms in terms of number and shape of the peaksof the obtained polymers by catalyst a. catalyst a produced linear oligomers contained linerolefinic part with a number average molecular weight in the range of 260 to 361.