title: Diffusion-regulated phase-transfer catalysis for atom transfer radical polymerization of methyl methacrylate in an aqueous/organic biphasic system.
abstract: A concept based on diffusion-regulated phase-transfer catalysis (DRPTC) in an aqueous-organic biphasic system with copper-mediated initiators for continuous activator regeneration is successfully developed for atom transfer radical polymerization (ICAR ATRP) (termed DRPTC-based ICAR ATRP here), using methyl methacrylate (MMA) as a model monomer, ethyl α-bromophenylacetate (EBrPA) as an initiator, and tris(2-pyridylmethyl)amine (TPMA) as a ligand. In this system, the monomer and initiating species in toluene (organic phase) and the catalyst complexes in water (aqueous phase) are simply mixed under stirring at room temperature. The trace catalyst complexes transfer into the organic phase via diffusion to trigger ICAR ATRP of MMA with ppm level catalyst content once the system is heated to the polymerization temperature (75 °C). It is found that well-defined PMMA with controlled molecular weights and narrow molecular weight distributions can be obtained easily. Furthermore, the polymerization can be conducted in the presence of limited amounts of air without using tedious degassed procedures. After cooling to room temperature, the upper organic phase is decanted and the lower aqueous phase is reused for another 10 recycling turnovers with ultra low loss of catalyst and ligand loading. At the same time, all the recycled catalyst complexes retain nearly perfect catalytic activity and controllability, indicating a facile and economical strategy for catalyst removal and recycling.
authors: Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
authors: Mingqiang
authors: M
authors: Ding
authors: Xiaowu
authors: X
authors: Jiang
authors: Jinying
authors: J
authors: Peng
authors: Lifen
authors: L
authors: Zhang
authors: Zhenping
authors: Z
authors: Cheng
authors: Xiulin
authors: X
authors: Zhu
mesh_terms: D002384:Catalysis; D004058:Diffusion; D005609:Free Radicals / Q000737:chemistry*; D007700:Kinetics; D020366:Methylmethacrylate / Q000737:chemistry*; D044367:Phase Transition; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D005609:Free Radicals; D011108:Polymers; D020366:Methylmethacrylate
keywords: atom transfer radical polymerization (ATRP); catalyst recycling; diffusion-regulated phase-transfer catalysis (DRPTC); initiators for continuous activators regeneration for atom transfer radical polymerization (ICAR ATRP)