Linear amphiphilic TEMPO-grafted poly(ether sulfone) as polymeric interfacial catalyst: Synthesis, self-assembly behavior, and application

.In this study, we report the development of a novel recyclable polymer-supported interfacial catalyst for Montanan oxidation. The catalyst was prepared by immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on poly(ether sulfone) (PES) bridged by imidazole groups and characterized by H-1 nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, elemental analysis, contact angle measurement, and, transmission electron microscopy (TEM). This well-designed polymer was self-assembled into nanoaggregates in CH2Cl2. It was then used as Pickering emulsifier in Montanari oxidation system (NaCIO/NaBr/immobilized TEMPO) for selective oxidation of different alcohols, which exhibited higher activity due to the enhanced mass transfer through microreactor mechanism. Moreover, this polymeric interfacial catalyst was pH-sensitive and could be easily recycled by adding small amount of acid, and subsequent cycles of alcohol oxidation showed no loss on either conversion or selectivity. This study represents an innovative approach for developing polymeric interfacial catalyst. (C) 2016 Elsevier B.V. All rights reserved.