Copolymerization of Ethylene and Propylene with the Sterically Hindered Monomer 3-Methyl-1-butene by Homogeneous Catalysis

Homogeneous catalysts in addition with MAO were used to synthesize copolymers of 3-methyl-1-butene (3MB1) with ethylene and propylene. Three series of ethylene/3MB1 copolymerizations were catalyzed by the organometallic compounds [Me 2 Si(Me 4 Cp)(N t Bu)]TiCl 2 ( 1 ), [Ph 2 Si(OctHFlu)(Ind)]ZrCl 2 ( 2 ), and rac -[Me 2 C(Ind) 2 ]ZrCl 2 ( 3 ). For the copolymerization of 3MB1 with propylene, the metallocenes rac -[Me 2 C(Ind) 2 ]ZrCl 2 ( 3 ) and [Me 2 C(Cp)(Flu)]ZrCl 2 ( 4 ) were used. For each metallocene, the influence of the molar fraction of 3MB1 in the feed as well as the influence of the polymerization temperature on the copolymerization behavior was investigated. In this regard copolymerization parameters were calculated. All copolymers were characterized by 13 C NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography techniques. Very small amounts of incorporated 3MB1 have a remarkable effect on the melting temperatures of the obtained polymers. Already by incorporation of 1 mol % of 3MB1 in the polymer, the melting temperature of the obtained LLDPE is lowered to 120 °C, whereas twice as much 1-butene is necessary to achieve the same effect, which should facilitate the processing.