Discovery and development of metallocene-basedpolyolefns with special properties

Beside Ziegler-Natta and Phillips catalysts the development of methylaluminoxane (MAO) as cocatalyst in combination with metallocenes or other transition metal complexes for the polymerization of olefns haswidely increased the possibilities in controlling the polymer composition, polymer structure, tacticity and specialproperties with high precision. These catalysts allow the synthesis of isotactic, isoblock, syndiotactic, stereoblockor atactic polymers, as well as polyolefn composite materials with superior properties such as flm clarity, tensilestrength and lower content of extractables. Metallocene and other single site catalysts are able to copolymerizeethene and propene with short and long chained a-olefns, cyclic olefns, or polar vinyl monomers such as ethers,alcohols or esters, especially, if the polar monomers are protected by aluminum alkyls. Different vinyl etherssuch as vinyl-ethyl ether, vinyl-propyl ether, vinyl-hexyl ether, and 2,7-octadienyl methyl ether (MODE) werecopolymerized with olefns using triisobutyl aluminum as protecting agents. Polar monomers could be incorporatedinto the polymer chain by up to 16 mol%. Such copolymers show better gas barrier and surface properties, aswell as solvent resistance and they are suitable for blends of polyolefns with polyethers and other polar polymersbecause of an excellent adhesion of the two polymers. Polyolefns J (2015) 2: 1-16

کلیدواژه ها:

methylaluminoxane ، metallocene catalysts ، olefn copolymerization ، polar monomers ، vinyl ethers