NU 2017-164
INVENTORS
Tobin Marks*
Tracy Lohr
Jiazhen Chen
SHORT DESCRIPTION
Active mono- and binuclear organoscandium complexes with a borate cocatalyst that enable ethylene + amino olefin copolymerizations in the absence of a Lewis-acidic masking reagent
BACKGROUND
Global polyolefin production reached about 150 million tons per year in 2015 and is still growing due to increasing market demand and lower feedstock prices. Introducing even a small percentage (< 2%) of polar functionality into the polyolefin backbone can dramatically enhance adhesion, compatibility with other polymers, and useful surface properties. Direct coordinative copolymerization of functionalized monomers with non-functionalized olefins is desirable for realizing precise control over such copolymer microstructures. Conventional d0 group 4 metal catalysts often require excess Lewis acidic “masking reagents” such as MAO (methylaluminoxane) or aluminum alkyls to prevent catalyst poisoning. This reduces process atom efficiency dramatically. Current generation less oxophilic late transition metal (Ni, Pd) catalysts exhibit higher tolerance towards polar functionalities, however, their activity and thermal stability are limited, and product polymer molecular weights are typically low.
ABSTRACT
Northwestern inventors have identified a novel method that overcomes the limitations of current approaches used to add functionality to polyolefins. The production of ethylene + amino olefins copolymers is enabled by coordinative polymerization catalyzed by rare earth catalysts. Amino-olefin incorporation in these copolymers approach 12%, and the product polymers have high molecular weights. Direct coordinative copolymerization of ethylene with functionalized comonomers is a long-sought approach to introducing polyolefin functionality. However, functional group Lewis basicity typically depresses catalytic activity and comonomer incorporations. Finding alternatives to intensively studied group 4 d0 and late transition metal catalysts is crucial to addressing this long-standing challenge. Northwestern researchers show that mono- and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino-olefin (AO; H2C=CH(CH2)nNR2) copolymerizations in the absence of a Lewis acidic masking reagent. Both activity (up to 4.2 × 102 kg/mol·h·atm) and AO incorporation (up to 2.0% at 0.1 M [AO]; up to 12% at 0.2 M [AO]) are appreciably significant. The binuclear catalysts exhibit enhanced AO tolerance and are able to incorporate longer chain amino olefins more appreciably than mononuclear catalyst.
APPLICATIONS
ADVANTAGES
IP STATUS
A PCT application has been filed.
PUBLICATIONS
Chen J, Gao Y, Wang B, Lohr T and Marks T (2017). Scandium-Catalyzed Self-Assisted Polar Co-monomer Enchainment in Ethylene Polymerization. Angewwandte Chemie International Edition. 56: 15964-15968.