Magnetic Janus nanocomposites with iridium() complexes for heterogeneous catalysis of logic controlled RAFT polymerization using multiplexed external switching

• Published in: Nanoscale Vol. 12; no. 14; pp. 7595 - 763
• Main Authors: Li, Xue, Ye, Sunjie, Zhang, Yu Chi, Zhao, Hong Peng, Huang, Ya, Zhang, Bin, Cai, Tao
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 14.04.2020
• Subjects: Addition polymerization; Catalysis; Catalysts; Chain transfer; Energy transfer; Iridium compounds; Iron oxides; Logic; Monomers; Multiplexing; Nanocomposites; Polymerization; Propagation (polymerization); Reagents; Switches; Switching; Vinyl acetate
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d0nr00402b

Photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization has emerged as a versatile and highly-efficient method for the polymerization of more activated monomers including N , N -dimethylacrylamide and methyl acrylate, and less activated monomers including N -vinylpyrrolidone and vinyl acetate, whilst imposing composition, sequence and spatiotemporal regulation. Although significant progress has been achieved in terms of ability to regulate PET-RAFT polymerization through the implementation of myriad environmental cues, it is still a great challenge to introduce multiple external switches within a single catalyst to accomplish logic toggling of controlled radical polymerization (CRP). Herein, we report the synthesis and characterization of Fe 3 O 4 @ a SiO 2 @PNMIr Janus nanocomposites coupled with immobilized heteroleptic iridium( iii ) complexes for heterogeneous catalysis of PET-RAFT polymerization. With this catalytic nanoarchitecture, we demonstrate multi-stimuli switching of CRPs using three different external physical manipulations: light "ON"/"OFF", magnet "OUT"/"IN" and temperature "LOW"/"HIGH". In addition, these magnetic Janus nanocomposites endowed radical polymerization with various attractive characteristics such as compatibility of myriad monomer formulations including "more activated" and "less activated" monomers, unique oxygen tolerance and ppm-level catalyst dosage. Logic-controlled polymerization with Fe 3 O 4 @ a SiO 2 @PNMIr nanocomposites provides a straightforward, robust and user-friendly strategy for realizing multiplexed external switching of polymer propagation using a single nanocatalyst without the involvement of exogenous reagents. Magnetic Janus nanocomposites enabled robust toggling of RAFT photopolymerization of myriad monomer formulations using a single nanocatalyst with three orthogonal external physical manipulations.