Transition-Metal-Catalyzed Functional Polyolefin Synthesis: Effecting Control through Chelating Ancillary Ligand Design and Mechanistic Insights

Abstract

The incorporation of polar functional groups into polyolefins can significantly alter the adhesion, barrier and surface properties, dyeability, printability, and compatibility of the resulting "functional polyolefin". Thus, the development of methods for the controlled synthesis of functional polyolefins from industrially relevant monomers holds the potential to expand the range of applications available to this already ubiquitous class of materials. In this Perspective, recent advances in transition-metal-catalyzed functional polyolefin synthesis will be reviewed. A common thread among the innovations discussed here is the perturbation of catalyst function by tailored design of the chelating ancillary ligand, aided in many cases by improved mechanistic understanding. Specific topics discussed here include rare examples of catalyst control over the regio-and stereochemistry of polar monomer insertion by phosphine−sulfonato palladium complexes (Drent-type), rate acceleration of insertion polymerization by binuclear cooperativity using salicylaldiminato nickel complexes (Grubbs-type), and formation of linear copolymers of ethylene and polar vinyl monomers using a cationic palladium catalyst ligated by a bisphosphine monoxide (BPMO) that contrasts the typical polymer microstructures formed by other cationic group 10 catalysts ligated by an α-diimine (Brookhart-type).

C−H Functionalization of Commodity Polymers

“…[74,77,78] Although significant effort has been devoted to this research area, state-of-the-art phosphine sulfonate (and related) palladium complexes produce materials of low molecular weight, realize only moderate functional group incorporation, and lack sufficient catalytic activities for industrial applications. [79][80][81][82] Post-polymerization modification of polyolefins transforms these high-volume and low-cost commodity polymers into value-added materials.The foundational challenge of this approach is the need to selectively functionalize unactivated CÀHbonds.T his compelling problem has led to anumber of contemporary approaches for the selective CÀHf unctionalization of polyolefins.B oaen and Hillmyer previously reviewed this area;t hus,t his section will focus primarily on work conducted since 2005. [75] Metal-catalyzed methods for the CÀHfunctionalization of complex small-molecule substrates have been the subject of numerous recent reports.…”

Group 4 metal complexes bearing the aminoborane motif: origin of tandem ring-opening metathesis/vinyl-insertion polymerization

“…The synthetic routes to Zr-1 and Hf-1 are shown in Scheme 1. Treatment of 3 with two equivalents of n-BuLi in toluene, followed by recrystallization from tetrahydrofuran/pentane 26 allowed isolating the ionic lithium complex (4) in 80% yield. For single-crystal X-ray analysis, see Figure S1, ESI.…”

“…3), single peaks in the GPC and the absence of glass transitions (T g ) that could be assigned to pure poly(NBE) ROMP further support the proposed polymer structures. [4][5][6][7][8][9] If successful, this approach would offer an alternative to currently investigated copolymerizations of ethylene with functional monomers such as acrylates. [4][5][6][7][8][9] If successful, this approach would offer an alternative to currently investigated copolymerizations of ethylene with functional monomers such as acrylates.…”

Reactivity Comparison of ω-Alkenols and Higher 1-Alkenes in Copolymerization with Propylene Using An Isospecific Zirconocene-MMAO Catalyst

“…The direct copolymerization of olefin with polar functional monomer is an efficient method for the synthesis of functionalized polyolefins with control of the amount of functional group and their distribution in the polymer backbone. The recent developments of single-site catalysts, based on metallocene catalyst, have achieved this copolymerization via coordination-insertion polymerization [3][4][5][6]. Late transition metal catalysts are widely applied in the area of the direct copolymerization of functional groups with ethylene, since they are more tolerant to the functional groups and thus applicable to copolymerize the polar functional monomers [5,6].…”

“…The recent developments of single-site catalysts, based on metallocene catalyst, have achieved this copolymerization via coordination-insertion polymerization [3][4][5][6]. Late transition metal catalysts are widely applied in the area of the direct copolymerization of functional groups with ethylene, since they are more tolerant to the functional groups and thus applicable to copolymerize the polar functional monomers [5,6]. Early transition metal catalysts require more complicated condition such as the use of functional group protection method, because these catalysts are more sensitive to the functional groups [3].…”