An Ionic Cluster Strategy for Performance Improvements and Product Morphology Control in Metal-Catalyzed Olefin-Polar Monomer Copolymerization.

Abstract

Product morphology control represents a critical challenge for polyolefin production, but it has remained largely unexplored in the field of ethylene-polar monomer copolymerization. Herein, an ionic cluster strategy was designed to control the product morphology during the synthesis of polar-functionalized polyolefins via precipitation polymerization. In addition to product morphology control, simultaneous improvements in the catalytic copolymerization performance (activities, copolymer molecular weights, and comonomer incorporation ratios) were achieved. These results were due to less poisoning of the metal-salt-based comonomers compared with their ester counterparts and the high local concentration of the alkene comonomers induced by ionic cluster formation. Moreover, the ionic cluster strategy is generally applicable to various comonomers and catalytic systems, greatly enhances the catalyst's thermal stability at high temperatures (90-150 °C), and enables the homopolymerization of both terminal and internal polar-functionalized olefins. Finally, polar-functionalized polyolefins and polyolefin composites (generated from a tandem process combining a prepolymerization step and subsequent polymerization) were developed, which showed tunable mechanical properties and great potential as compatibilizing agents for mixtures of polyolefins and other types of polymers.