Transition Metal Catalyst Separation and Recycling: Recent Progress in TPSC-based ATRP

Transition metal-mediated atom transfer radical polymerization (ATRP) is well known as one of successful reversible deactivation radical polymerizations for synthesizing various designable structures. However, the resultant polymers are usually contaminated or colored by large amounts of metal catalyst, which does not facilitate its industrialization. How to efficiently separate and recycle the metal catalyst has triggered lots of interest in green chemistry and ATRP. In this review, we mainly focus on a recyclable liquid/liquid thermo-regulated phase separable catalysis (TPSC) strategy applied in ATRP, which provides a facile and efficient method combining homogeneous reaction with heterogeneous separation just by simply changing temperature. TPSC-based ATRP systems include but not limit to the following systems: fluorous biphasic system, lower alcohol/alkane biphasic system, poly(ethylene glycol) (PEG) biphasic system and thermo-regulated ionic liquids biphasic system and so on.