Synergetic Effect of Monomer Functional Group Coordination in Catalytic Insertion Polymerization.

PhS- and PhNH-functionalized dienes are copolymerized efficiently with butadiene to stereoregular copolymers by [(mesitylene)Ni(allyl)][BArF4] (Ni-1). Overall polymerization rates and comonomer incorporations depend strongly on the linker length between the diene moiety and functional group, in, e.g., PhS-(CH2)xC(═CH2)-CH═CH2 (PhS-x-BD, x = 3-7), in particular for certain linker lengths high comonomer reactivity ratios stand out. This effect is related to a favorable binding of the comonomer to the active site comprising coordination of its functional group, which significantly enhances comonomer incorporation in the growing polymer chain.

Direct Synthesis of Imidazolium-Functional Polyethylene by Insertion Copolymerization.

Cationic imidazolium-functionalized polyethylene is accessible by insertion copolymerization of ethylene and allyl imidazolium tetrafluoroborate (AIm-BF4 ) with phosphinesulfonato palladium(II) catalyst precursors. Imidazolium-substituted repeat units are incorporated into the main chain and the initiating saturated chain end of the linear polymers, rather than the terminating unsaturated chain end. The counterion of the allyl imidazolium monomer is decisive, with the chloride analogue (AIm-Cl) no polymerization is observed. Stoichiometric studies reveal the formation of an inactive chloride complex from the catalyst precursor. An effect of moderate densities (0.5 mol%) of ionic groups on the copolymers' physical properties is exemplified by an enhanced wetting by water.

Stereoselective Copolymerization of Butadiene and Functionalized 1,3-Dienes.

[(Mesitylene)nickel(allyl)+][BArF4-] (Ni-1) catalyzes the 1,4-cis selective copolymerization of isoprene and 1,3-butadiene with 15 (RO)3Si-, R2N-, RSO2-, RSO2NH-, and (RO)2B-functionalized 1,3-dienes. Incorporation of the functionalized 1,3-diene occurs very efficiently with high comonomer conversions, as observed, for example, for copolymerizations of 1,3-butadiene with (EtO)3Si(CH2)3C(═CH2)CH═CH2 (1), PhS(O)2(CH2)3C(═CH2)-CH═CH2 (7), or (pinB)C(═CH2)C(CH3)═CH2 (15), while copolymerization rates vary from strongly to slightly decreased when compared to butadiene homopolymerizations.