A series of pyridine-imine [N-N] ligands are efficiently prepared through the condensation reaction of ketone/aldehyde precursor and synthesized aniline. The ligands -L, n = 1–4- are corresponding nikel complexes -Cn, n=1-4- are characterized and used for polymerization of ethylene in the presence of modified methylaluminoxane as cocatalyst. The produced low density polyethylenes show at least 21 branches per 1000 carbon atoms with Mv values up to 80.0 × 104 n, n = 1–4-. Aldimino-based catalyst is more active than the analogue catalyst, although, ketimines result in polyethylene with higher Mv. Nevertheless, the product of aldimino-based catalyst indicates the highest melting point of 132.3 °C but ketimine exhibits the highest crystallinity of 32.98% at the same polymerization conditions. Specific morphologies including smooth spherical and irregular porous particles are observed for some polymer samples. However, at high polymerization temperatures and different monomer pressures, different morphologies as well as two melting point peaks are observed in scanning electron microscopy -SEM- images and differential scanning calorimeter thermograms, respectively.

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