A Synthetic Polyester from Plant Oil Feedstock by Functionalizing Polymerization

Catalytic functionalization/polymerization of castor oil‐derived undecenol yields an aliphatic polyester in a single step under mild conditions. The key to selective formation of linear high melting polyester is highly active carbonylation catalysts that at the same time do not undergo strong isomerization.     

Direct synthesis of ethylene-acrylic acid copolymers by insertion polymerization

Neutral palladium(II) phosphinesulfonato polymerization catalysts were found to be stable toward carboxylic acid moieties and to enable direct linear copolymerization of ethylene with acrylic acid.     

Which Polyesters Can Mimic Polyethylene?

Self‐metathesis of erucic acid by [(PCy₃)(η‐C‐C₃H₄N₂Mes₂)Cl₂Ru = CHPh] (Grubbs second‐ generation catalyst) followed by catalytic hydrogenation and purification via the ester yields 1,26‐hexacosanedioate (>99% purity). Polyesterification with 1,26‐hexacosanediol, generated from the diester, affords polyester‐26,26, which features a T_m of 114 °C (T_c = 92 °C, ΔH_m = 160 J g⁻¹). Ultralong‐chain model polyesters‐38,23 (T_m = 109 °C) and −44,23 (T_m = 111 °C), generated via multistep procedures including acyclic diene metathesis polymerization, underline that melting points of such aliphatic polyesters do not gradually increase with methylene sequence chain length. Available data suggest that to mimic linear polyethylenes thermal properties, even longer sequences, amounting to at least four times a fatty acid chain, fully incorporated in a linear fashion are required.     

Synthesis and properties of highly branched polycations with an aliphatic polyether scaffold

Cationic polyelectrolytes with pyridinium and 1,2‐dimethylimidazolium functionalities based on a hyperbranched polyglycerol scaffold with a narrow polydispersity were prepared by a polymer analogous reaction in a one‐pot synthesis. By the variation of the spacer lengths between the cationic functionalities and polyether scaffold, a simple method was developed to adjust the charge density and flexibility of the polycations, as reflected by their glass‐transition temperature. The polyelectrolytes were further characterized in detail by ¹H NMR, ¹³C NMR, and IR spectroscopy, as well as thermogravimetric analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4609–4617, 2005     

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.

     

Aqueous Catalytic Polymerization of Olefins

Catalytic conversions in aqueous environments by transition metal complexes have become a well‐established field over the past two decades. However, the vast majority of investigations have focussed on small‐molecule synthesis. This may appear somewhat surprising as water is a particularly attractive reaction medium, especially for polymerization reactions. For example, aqueous emulsion and suspension polymerization is carried out today on a large scale by noncatalytic free‐radical routes. Polymer latices can be obtained as a product, that is, stable aqueous dispersions of polymer particles in the size range of 50 to 1000 nm. Such latices possess a unique property profile. Amongst other advantages, the use of water as a dispersing medium is particularly environmentally friendly. In comparison to these free‐radical reactions, aqueous catalytic polymerizations of olefinic monomers have received less attention. However, considerable advances and an increased awareness of this field have emerged during the past few years. A variety of high molecular weight polymers ranging from amorphous or semicrystalline polyolefins to polar‐substituted hydrophilic materials have now been prepared by catalytic polymerization of olefinic monomers in water. Polymer latices based on a number of readily available monomers are accessible and catalytic activities as high as 10⁵ turnovers per hour have already been reported. As another example, materials prepared by aqueous catalytic polymerization have been investigated as protein inhibitors. A versatile field spanning colloids, polymer, and coordination chemistry has emerged.