NHC-Metallosurfactants as Active Polymerization Catalysts.

Next-generation surfactants provide extended functionality apart from their amphiphilic properties. We present two novel metallosurfactants characterized by an N-heterocyclic carbene (NHC) head bearing Cu(I) and Fe(II). An innovative approach for their application in emulsion polymerizations under atom transfer radical polymerization (ATRP) conditions was developed. Thereby the complexes fulfilled the role of emulsifiers, active catalysts, and stabilization agents at once. Polymerization of methyl methacrylate (MMA) yielded stable poly(methyl methacrylate) (PMMA) colloids in water with the catalyst located at the surface of the colloids. The termination of PMMA with a bromine moiety enabled the subsequent copolymerization with styrene via macroinitiation and PMMA-polystyrene (PS) core-shell particles were obtained. Gel permeation chromatography (GPC) and selective gradient NMR experiments revealed a covalent linkage between the PMMA core and the PS shell.