424902 CO2-Responsive Polymer Supported Au Used As Easily Reusable Catalyst in Aqueous Media

Sunday, November 8, 2015: 4:30 PM
355E (Salt Palace Convention Center)
Yuchen Zhang, Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China, Wen-Jun Wang, State Key Laboratory of Chemical Engineering, Zhejiang University, Hangzhou, China, Bo-Geng Li, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China and Shiping Zhu, Department of Chemical Engineering, McMaster University, Hamilton, ON, Canada

Gold catalysts have an outstanding catalytic activity when well dispersed in its nanoparticle form (<10nm). In this work, we developed a series of CO2-responsive star polymer-supported Au as easily-recyclable catalysts in water by simply bubbling CO2 and N2. The polymers consisted of a hyperbranched polyethylene(HBPE) core and multiple  poly(2-(dimethylamino)ethyl methacrylate-2-(Diethylamino)ethyl methacrylate) (PDMAEMA-DEAEMA) arms, and were synthesized through a sequential Pd-catalyzed chain walking copolymerization of ethylene and 2-(2-bromoisobutyryloxy)ethyl acrylate, followed by atom-transfer radical polymerization with DMAEMA and DEAEMA. The samples had a molecular weight between 12-40kg/mol with fDMAEMA/DEAEMA making up 41-74 wt%, and could be easily dispersed in water to form micelles of several hundred nanometers. The catalysts were used for the reduction of 4-nitrophenol in water, and were recycled by purging CO2/N2. Catalysts with fDMAEMA/DEAEMA making up 45-65wt% performed well, however higher values may have prevented reactant contact with the Au catalyst. The catalysts can be reused several times (up to 15 times) with a concentration of approximately 15ppm and with very little catalysis activity loss. These catalysts demonstrated higher catalytic activity than previously reported supported Au catalysts and good CO2 switchability.

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