L-menthol and thymol eutectic mixture as a bio-based solvent for the "one-pot" synthesis of well-defined amphiphilic block copolymers by ATRP

A bio-based eutectic mixture (EM), composed of L-menthol and thymol was used, for the first time, as solvent for the atom transfer radical polymerization (ATRP) of hydrophobic monomers (methyl acrylate (MA), methyl methacrylate (MMA), 2-(dimethylamino) ethyl methacrylate (DMAEMA), glycidyl methacrylate (GMA)) and hydrophilic monomers (2-hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methyl ether acrylate (OEOA)). Well-defined homopolymers (1.02 < D < 1.47) were obtained using only 225 ppm of copper catalyst and a monomer/EM ratio (v/v) of 0.75. As a proof-of-concept, this new polymerization system allowed the preparation of well-defined amphiphilic block copolymers (ABs) of PMA-b-PHEA-Br, PMA-b-POEOA-Br and PDAMEMA-b-PHEA-Br by "one-pot" supplemental activator and reducing agent (SARA) ATRP, as well as a PMA-b-PHEA-b-PBA-Br triblock copolymer, after chain extension of a PMA-b-PHEA-Br diblock copolymer. The use of a unique solvent system opens a new route for the easy synthesis of ABs, with conditions that can be applied in large scale production.