Highly active,thermo‐responsive polymeric catalytic system for reuse in aqueous and organic CuAAC reactions

Tris‐(benzyltriazolylmethyl)amine (TBTA) has been immobilized onto a styrenic monomer and subsequently copolymerized with N‐isopropyl acrylamide (NIPAM) to afford catalytically active thermo‐responsive copolymers for copper assisted click chemistry. P(TBTA‐co‐NIPAM) copolymers were synthesized with incorporation of between 2 and 10 ligand units per chain and tuneable molecular weight (28–148 kDa). A combination of ¹H NMR spectroscopy, size exclusion chromatography (SEC) and elemental analysis (EA) confirmed the controlled synthesis of these polymers and allowed for quantification of the degree of TBTA‐functionalized monomer incorporation. After loading with copper(I) bromide, this homogeneous catalyst system was added to a water/ethyl acetate two‐phase system. Using this biphasic system aqueous click reactions could be performed at room temperature, while organic click chemistry could be performed above the cloud point temperature of the catalyst system. The polymer catalyst system could be regenerated via extraction by making use of its lower critical solution temperature (LCST)‐behavior, and then reused for further copper(I) catalyzed azide‐alkyne cycloaddition (CuAAC) reactions. While a reduced catalytic activity is observed as a result of copper leaching in aqueous click reactions, the recycling experiments in the organic phase demonstrated that this copolymer supported system allows for efficient recycling and reuse. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011