Renewing polyethylene: Insertion copolymerization of sugar derived hydrophilic monomers with ethylene

Steric Influences on Chain Microstructure in Palladium-Catalyzed α-Olefin (Co)polymerization: Unveiling the Steric-Deficient Effect

This study addresses the challenge of controlling branching density and branch-type distribution in late-transition-metal-catalyzed chain walking polymerizations. We explored α-diimine Pd(II) complexes with incrementally increased ortho-aryl sterics for long-chain α-olefin (co)polymerization. Pd0-Pd3 catalysts, which feature gradually increased ortho-aryl sterics and at least one small CH3 substituent, exhibited similar 2,1-insertion fractions (44-50%), polymer branching densities (55-63/1000C), and melting temperatures (26-28 °C). In contrast, Pd4 with bulky ortho-aryl sterics covering all sides demonstrated a significant increase in 2,1-insertion fractions up to 82%, leading to "PE-like" polymers with high melting temperatures (Tm > 111 °C). This abrupt change in polymerization behavior, termed the "steric-deficient effect", contrasts with the gradual changes observed in similar Ni(II) systems that we reported previously. Furthermore, due to the rapid chain walking ability of Pd(II) catalysts in long-chain α-olefin (co)polymerization, these catalysts favor the production of polyolefins with higher proportions of methyl branches compared to those produced by Ni(II) catalysts. Particularly, these Pd(II) catalysts are capable of synthesizing functionalized semicrystalline copolymers by copolymerizing 1-octene with a variety of polar comonomers, thereby significantly altering the surface properties of the materials.

Polar-Functionalized Polyethylenes Enabled by Palladium-Catalyzed Copolymerization of Ethylene and Butadiene/Bio-Based Alcohol-Derived Monomers

Polar-functionalized polyolefins are high-value materials with improved properties. However, their feedstocks generally come from non-renewable fossil products; thus, it requires the development of renewable bio-based monomers to produce functionalized polyolefins. In this contribution, via the Pd-catalyzed telomerization of 1,3-butadiene and three types of bio-based alcohols (furfuryl alcohol, tetrahydrofurfuryl alcohol, and solketal), 2,7-octadienyl ether monomers including OC8-FUR, OC8-THF, and OC8-SOL were synthesized and characterized, respectively. The copolymerization of these monomers with ethylene catalyzed by phosphine-sulfonate palladium catalysts was further investigated. Microstructures of the resultant copolymers were analyzed by NMR and ATR-IR spectroscopy, revealing linear structures with incorporations of difunctionalized side chains bearing both allyl ether units and polar cyclic groups. Mechanical property studies exhibited better strain-at-break of these copolymers compared to the non-polar polyethylene, among which the copolymer E-FUR with the incorporation of 0.3 mol% displayed the highest strain-at-break and stress-at-break values of 940% and 35.9 MPa, respectively.

Recent Advances in the Copolymerization of Ethylene with Polar Comonomers by Nickel Catalysts

The less-expensive and earth-abundant nickel catalyst is highly promising in the copolymerization of ethylene with polar monomers and has thus attracted increasing attention in both industry and academia. Herein, we have summarized the recent advancements made in the state-of-the-art nickel catalysts with different types of ligands for ethylene copolymerization and how these modifications influence the catalyst performance, as well as new polymerization modulation strategies. With regard to α-diimine, salicylaldimine/ketoiminato, phosphino-phenolate, phosphine-sulfonate, bisphospnine monoxide, N-heterocyclic carbene and other unclassified chelates, the properties of each catalyst and fine modulation of key copolymerization parameters (activity, molecular weight, comonomer incorporation rate, etc.) are revealed in detail. Despite significant achievements, many opportunities and possibilities are yet to be fully addressed, and a brief outlook on the future development and long-standing challenges is provided.

Renewable Polyurethanes from Sustainable Biological Precursors

Due to the depletion of fossil fuels, higher oil prices, and greenhouse gas emissions, the scientific community has been conducting an ongoing search for viable renewable alternatives to petroleum-based products, with the anticipation of increased adaptation in the coming years. New academic and industrial developments have encouraged the utilization of renewable resources for the development of ecofriendly and sustainable materials, and here, we focus on those advances that impact polyurethane (PU) materials. Vegetable oils, algae oils, and polysaccharides are included among the major renewable resources that have supported the development of sustainable PU precursors to date. Renewable feedstocks such as algae have the benefit of requiring only sunshine, carbon dioxide, and trace minerals to generate a sustainable biomass source, offering an improved carbon footprint to lessen environmental impacts. Incorporation of renewable content into commercially viable polymer materials, particularly PUs, has increasing and realistic potential. Biobased polyols can currently be purchased, and the potential to expand into new monomers offers exciting possibilities for new product development. This Review highlights the latest developments in PU chemistry from renewable raw materials, as well as the various biological precursors being employed in the synthesis of thermoset and thermoplastic PUs. We also provide an overview of literature reports that focus on biobased polyols and isocyanates, the two major precursors to PUs.

Synthesis and melt-spinning of partly bio-based thermoplastic poly(cycloacetal-urethane)s toward sustainable textiles

Partly bio-based thermoplastic poly(cycloacetal-urethane)s synthesized and melt-spun into textile fibres that can be potentially chemically recycled.

Custom-made polar monomers utilized in nickel and palladium promoted olefin copolymerization

In this review, the functions of custom-made polar monomers are insightfully emphasized in the preparation of functional polyolefins.