Block Copolymers Based on Ethylene and Methacrylates Using a Combination of Catalytic Chain Transfer Polymerisation (CCTP) and Radical Polymerisation.

Two scalable polymerisation methods are used in combination for the synthesis of ethylene and methacrylate block copolymers. ω-Unsaturated methacrylic oligomers (MMAn ) produced by catalytic chain transfer (co)polymerisation (CCTP) of methyl methacrylate (MMA) and methacrylic acid (MAA) are used as reagents in the radical polymerisation of ethylene (E) in dimethyl carbonate solvent under relatively mild conditions (80 bar, 70 °C). Kinetic measurements and analyses of the produced copolymers by size exclusion chromatography (SEC) and a combination of nuclear magnetic resonance (NMR) techniques indicate that MMAn is involved in a degradative chain transfer process resulting in the formation of (MMA)n -b-PE block copolymers. Molecular modelling performed by DFT supports the overall reactivity scheme and observed selectivities. The effect of MMAn molar mass and composition is also studied. The block copolymers were characterised by differential scanning calorimetry (DSC) and their bulk behaviour studied by SAXS/WAXS analysis.

Statistical and Block Copolymers of Ethylene and Vinyl Acetate via Reversible Addition-Fragmentation Chain Transfer Polymerization.

A dithiocarbamate chain transfer agent (CTA) based on Z-group substituted with a diphenyl amine (-NPh2 ) moiety is selected for the synthesis of statistical and diblock copolymers of ethylene and vinyl acetate via reversible addition-fragmentation chain transfer polymerization. Benefiting from the good chain growth control of polyethylene (PE), poly(vinyl acetate) (PVAc), and poly(ethylene-co-vinyl acetate) (EVA) achieved with this CTA, linear diblock copolymers of the type EVA-b-PE, EVA-b-EVA, and PVAc-b-EVA are successfully synthesized. A three-arm EVA star is additionally obtained starting from a trifunctional dithiocarbamate CTA.

Ethylene Polymerization-Induced Self-Assembly (PISA) of Poly(ethylene oxide)-block-polyethylene Copolymers via RAFT.

Poly(ethylene oxide) (PEO) with dithiocarbamate chain ends (PEO-SC(=S)-N(CH3 )Ph and PEO-SC(=S)-NPh2 , named PEO-1 and PEO-2, respectively) were used as macromolecular chain-transfer agents (macro-CTAs) to mediate the reversible addition-fragmentation chain transfer (RAFT) polymerization of ethylene in dimethyl carbonate (DMC) under relatively mild conditions (80 °C, 80 bar). While only a slow consumption of PEO-1 was observed, the rapid consumption of PEO-2 led to a clean chain extension and the formation of a polyethylene (PE) segment. Upon polymerization, the resulting block copolymers PEO-b-PE self-assembled into nanometric objects according to a polymerization-induced self-assembly (PISA).