Coordinative Chain Transfer and Chain Shuttling Polymerization

Coordinative chain transfer polymerization, CCTP, is a degenerative chain transfer polymerization process that has a wide range of applications. It allows a highly controlled synthesis of polyolefins, stereoregular polydienes, and stereoregular polystyrene, including (stereo)block as well as statistical copolymers thereof. It also shows a green character by allowing catalyst economy during the synthesis of such polymers. CCTP notably allows the end functionalization of both the commodity and stereoregular specialty polymers aforementionned, control of the composition of statistical copolymers without adjusting the feed, and quantitative formation of 1-alkenes from ethene. A one-pot one-step synthesis of the original multiblock microstructures and architectures by chain shuttling polymerization (CSP) is also an asset of CCTP. This methodology takes advantage of the simultaneous presence of two catalysts of different selectivity toward comonomers that produce blocks of different composition/microstructure, while still allowing the chain transfer. This affords the production of highly performant functional polymers, such as thermoplastic elastomers and adhesives, among others. This approach has been extended to cyclic esters' and ethers' ring-opening polymerization, providing new types of multiblock microstructure. The present Review provides the state of the art in the field with a focus on the last 10 years.

The emerging applications of click chemistry reactions in the modification of industrial polymers

Click chemistry reactions have been applied to the modification of major industrial polymers by analysing the synthetic approaches and the resulting material properties.

Synthesis and Functionalization of Porphyrins through Organometallic Methodologies

This review focuses on the postfunctionalization of porphyrins and related compounds through catalytic and stoichiometric organometallic methodologies. The employment of organometallic reactions has become common in porphyrin synthesis. Palladium-catalyzed cross-coupling reactions are now standard techniques for constructing carbon-carbon bonds in porphyrin synthesis. In addition, iridium- or palladium-catalyzed direct C-H functionalization of porphyrins is emerging as an efficient way to install various substituents onto porphyrins. Furthermore, the copper-mediated Huisgen cycloaddition reaction has become a frequent strategy to incorporate porphyrin units into functional molecules. The use of these organometallic techniques, along with the traditional porphyrin synthesis, now allows chemists to construct a wide range of highly elaborated and complex porphyrin architectures.

Polyethylene-g-Polystyrene Copolymers by Combination of ROMP, Mn2(CO)10-Assisted TEMPO Substitution and NMRP

The synthesis of polyethylene-graft-polystyrene copolymers by a multistep "grafting from" approach is described. In the first step, a bromo-functional polyethylene (PE-Br) was synthesized via ring-opening metathesis polymerization (ROMP) of cis-cyclooctene (COE) and quantitative hydrobromination. Subsequent irradiation of PE-Br under visible light in the presence of dimanganese decacarbonyl (Mn₂(CO)₁₀) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) resulted in the formation of TEMPO-substituted polyethylene (PE-TEMPO). Polystyrene (PS) chains were then grown via nitroxide mediated radical polymerization (NMRP) from the PE-TEMPO precursor to give desired PE-g-PS copolymers in a controlled manner. The intermediates at each step and final graft copolymers were characterized by ¹H NMR, FT-IR, GPC, and DSC analyses.

Divinyl-end-functionalized polyethylenes: ready access to a range of telechelic polyethylenes through thiol-ene reactions

Telechelic α,ω-iodo-vinyl-polyethylenes (Vin-PE-I) were obtained by catalytic ethylene polymerization in the presence of [(C5 Me5 )2 NdCl2 Li(OEt2 )2 ] in combination with a functionalized chain-transfer agent, namely, di(10-undecenyl)magnesium, followed by treatment of the resulting di(vinylpolyethylenyl)magnesium compounds ((vinyl-PE)2 Mg) with I2 . The iodo-functionalized vinylpolyethylenes (Vin-PE-I) were transformed into unique divinyl-functionalized polyethylenes (Vin-PE-Vin) by simple treatment with tBuOK in toluene at 95 °C. Thiol-ene reactions were then successfully performed on Vin-PE-Vin with functionalized thiols in the presence of AIBN. A range of homobifunctional telechelic polyethylenes were obtained on which a hydroxy, diol, carboxylic acid, amine, ammonium chloride, trimethoxysilyl, chloro, or fluoroalkyl group was installed quantitatively at each chain end.

Facile synthesis of chain end functionalized polyethylenes via epoxide ring-opening and thiol–ene addition click chemistry

A library of low MW chain end functionalized polyethylenes with narrow MW distributions were prepared under mild conditions.

Synthesis of low dispersity star-like polyethylene: a combination of click chemistry and a sol–gel process

Low dispersity star-like polyethylene was synthesized via a facile sol–gel process using trimethoxysilane-terminated polyethylene derived from thiol-ene click chemistry.