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This paper presents the synthesis of two aminosilane-based external donors for the Ziegler-Natta catalysis: di(piperidyl) dimethoxysilane (DPPDMS) and dipyrrolyldimethoxysilane (DPRDMS). We compared the electron donation by these two compounds in the MgCl2- supported Ziegler-Natta catalysis of the polymerization of hexene-1 into a polyhexene-1 (PHe) elastomer with that of the common donor cyclohexylmethyldimethoxysilane (CHMMS). The catalytic activity of the system and isotacticity of the polymer (PHe) product improved significantly because of the considerable steric hindrance and strong electronic effects of these aminosilane-based external donors. The effects of different external donors on the catalytic efficiency, polymer isotacticity, molecular weight and molecular weight distribution of the PHe products were investigated. Under the best reaction conditions, the catalyst activity, polymer molecular weight, and glass-transition temperature were determined as 899 g/g Cat·h-1, MW = 252,300 g/mol, and -41.39°C, respectively. The PHe was characterized by FTIR and NMR. This report also describes blending of PHe and low density polyethylene that leads to a significant increase in the impact strength and elongation at breaks.

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