%0 Journal Article
%T Highly branched polyethylene oligomers via group IV-catalysed polymerization in very nonpolar media
%J -
%D 2019
%R https://doi.org/10.1038/s41929-018-0224-0
%X Early transition metal catalysts produce high-density and linear low-density polyethylenes with spectacular efficiency. Nevertheless, these catalysts are ineffective in producing low-density polyethylene homopolymers with large ¨C(CH2)xCH3 branch densities (x£¿¡Ý£¿5) or low-molecular-mass (Mn£¿<£¿1,200£¿g£¿mol£¿1) highly branched polyethylenes (HBPEs). The latter are potential alternative synthetic lubricants that have eluded efficient catalytic synthesis. Here we report the synthesis of low-Mn HBPEs with 61¨C93 branches per 1,000 carbon atoms from abundant ethylene as the primary feedstock using a soluble, highly active ion-paired organozirconium catalyst in a saturated hydrocarbon solvent. The unprecedented activity and branch selectivity reflect previously unrecognized aspects of the cationic catalyst¨Ccounteranion pairing in nonpolar media and are characterized spectroscopically and quantum mechanically. The HBPE products are rheologically and tribologically attractive candidates for synthetic lubricants
%U https://www.nature.com/articles/s41929-018-0224-0