Macromolecular Rapid Communications, Vol.37, No.16, 1337-1343, 2016
Highly Efficient and Facile Photocatalytic Recycling System Suitable for ICAR ATRP of Hydrophilic Monomers
Photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (ATRP) of hydrophilic monomers in heptane/ethanol latent-biphasic system for copper catalyst separation and recycling have been realized for the first time at room temperature with different wavelengths of visible light LED (green, blue, purple, and white LED) as external stimulus, using 2-bromophenylacetate as the ATRP initiator and camphorquinone/triethylamine as the photoinitiator. In this system, hybrid catalyst complex (HCc) is synthesized as a novel nonpolar catalyst, which is preferentially dissolved in heptane. The hydrophilic polymers obtained catalyzed by HCc in heptane/ethanol mixture solvent show typical living features, for example, the values of M-n,M-GPC increase linearly with monomer conversion up to quantitative level (>96%) and the molecular weight distributions were kept narrow (M-w/M-n < 1.20) throughout the polymerization process. It should be noted that the excellent controllability of this novel polymerization system can be achieved even after 5 catalyst recycling experiments under LED irradiation.
Keywords:atom transfer radical polymerization (ATRP);catalyst recycling;hydrophilic monomers;latent-biphasic catalysis;visible light induced ATRP