A sustainable photocontrolled ATRP strategy: facile separation and recycling of a visible-light-mediated catalyst fac-[Ir(ppy)3]

Facile catalyst separation and recycling is a challenging topic for the transition-metal mediated polymerization of water-soluble monomers. In this work, a photoinduced iridium-based water-induced phase separable catalysis for atom transfer radical polymerization (WPSC ATRP) system has been established under blue light-emitting diode (LED) irradiation, using water-soluble poly(ethylene glycol) methyl ether (meth)acrylate (PEGMA and PEGA) as the model monomer, ethyl α-bromophenylacetate (EBPA) as an initiator, tris(2-phenylpyridine)iridium (fac-[Ir(ppy)3]) as a catalyst, and 1,2-dichlorobenzene/ethanol as the co-solvent. After polymerization, pure water was added in this polymerization system to induce the phase separation, and the Ir catalyst in the 1,2-dichlorobenzene phase could be easily separated in situ for recycling. Attractive features of the constructed visible-light-mediated catalyst separation and recycling ATRP system include the feasibility of visible light irradiation, high catalytic activity, good control over molecular weights and distributions, attractive “living” characteristics, efficient separation capacity, low metal residues and more catalyst reuse cycles.