Diminishing the catalyst concentration in the Cu(0)‐RDRP and ATRP synthesis of well‐defined low‐molecular weight poly(glycidyl methacrylate)

Abstract

AbstractLow‐molecular weight (MW) solvent‐borne functional (meth)acrylic polymers find an important use in coating resins. However, when preparing such polymers through copper‐mediated reversible‐deactivation radical polymerization (RDRP), contamination with colored copper species and the use of expensive ligands represent significant obstacles from the industrial application viewpoint. Here, we investigated the possibilities of diminishing the catalyst levels in metallic coper‐mediated RDRP (Cu(0)‐RDRP) and atom transfer radical polymerization (ATRP) of a widely used functional monomer, glycidyl methacrylate (GMA), targeting a low MW of approximately 3000. Both Cu wire‐ and powder‐catalyzed Cu(0)‐RDRP provided well‐defined, low‐MW poly(GMA) at quantitative conversions when using an inexpensive PMDETA ligand in DMSO. However, only with Cu powder, the contamination of the final polymerization mixture with Cu species could be efficiently diminished to ≤66 ppm while maintaining the polymerization control. Additionally, the in situ block copolymerization was successfully demonstrated, furnishing a poly(GMA)‐b‐poly(MMA) mixture containing only 39 ppm of Cu in a process facilitated by the intrinsic reductive properties of the GMA's epoxide groups. Significantly, the targeted low‐MW poly(GMA) could also be synthesized by low‐catalyst‐concentration ATRP (CuBr/PMDETA system), obtaining well‐defined polymers with quantitative conversions at ca 50 ppm of Cu in the final mixture, both at r.t. and 50 °C.