Late-transition-metal
catalysts have great potentials to incorporate
polar comonomers during olefin polymerization. The preparation of
polar-functionalized polyolefins with different microstructures and
topologies is a highly fascinating concept. In this contribution,
we demonstrate this possibility through palladium-catalyzed ethylene
copolymerizations with polar-functionalized α-olefins and their
terpolymerizations with α-olefins. A phosphine–sulfonate–palladium
catalyst (PO-Pd) afforded highly linear polyethylene
during ethylene homopolymerization. Linear low-density polyethylene
(LLDPE) was obtained from the PO-Pd-catalyzed copolymerizations
of ethylene with α-olefins; in these copolymerizations, the
partial or complete replacement of α-olefins with polar-functionalized
α-olefins led to the formation of polar-functionalized LLDPE
(P-LLDPE). A specially designed α-diimine palladium catalyst
(NN-Pd) afforded polyethylenes with tunable branching
densities (16–37 per 1000 carbon atoms), melting points (101–113
°C), and densities (0.89–0.92 g/cm3), which
closely resemble those of low-density polyethylene (LDPE). The NN-Pd-catalyzed copolymerizations of ethylene with polar α-olefins
generated analogues of polar-functionalized low-density polyethylene
(P-LDPE). The mechanical and surface properties of these polar polyolefin
materials were studied in detail, and their properties were further
improved/modified through cross-linking reactions.
The incorporation of comonomers during ethylene polymerization can efficiently modulate important material properties of the polyolefins. Utilizing bioresourced comonomers for the generation of high‐performance polyolefin materials is attractive from a sustainability point of view. In this contribution, bioresourced eugenol and related comonomers were incorporated into polyolefins through palladium‐catalyzed copolymerization and terpolymerization reactions. Importantly, high‐molecular‐weight catechol‐functionalized polyolefins can be generated. The introduction of different metal ions induces efficient interactions with the incorporated catechol groups, leading to enhanced mechanical properties and self‐healing properties. Moreover, the catechol functionality can greatly improve other properties such as surface properties, adhesion properties, and compatibilizing properties. The catechol‐functionalized polyolefin was demonstrated as a versatile platform polymer for accessing various materials with dramatically different properties.
In this work, ethylene copolymerization and terpolymerization reactions with some nitrogen-containing monomers were investigated using α-diimine palladium and phosphine-sulfonate palladium catalysts.
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