Preparation of hyperstar polymers with encapsulated Au25(SR)18 clusters as recyclable catalysts for nitrophenol reduction

Daqiao Hu; Shan Jin; Yi Shi; Xiaofeng Wang; Robert W Graff; Wenqi Liu; Manzhou Zhu; Haifeng Gao

doi:10.1039/c6nr09727h

Preparation of hyperstar polymers with encapsulated Au₂₅(SR)₁₈ clusters as recyclable catalysts for nitrophenol reduction

Nanoscale. 2017 Mar 9;9(10):3629-3636. doi: 10.1039/c6nr09727h.

Authors

Daqiao Hu¹, Shan Jin², Yi Shi³, Xiaofeng Wang³, Robert W Graff³, Wenqi Liu³, Manzhou Zhu², Haifeng Gao³

Affiliations

¹ Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA. hgao@nd.edu and School of Chemistry and Chemical Engineering & Center for Atomic Engineering of Advanced Materials, Anhui University, Hefei 230039, China. zmz@ahu.edu.cn.
² School of Chemistry and Chemical Engineering & Center for Atomic Engineering of Advanced Materials, Anhui University, Hefei 230039, China. zmz@ahu.edu.cn.
³ Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA. hgao@nd.edu.

PMID: 28247888
DOI: 10.1039/c6nr09727h

Abstract

A robust approach is developed to prepare hyperstar polymer-Au₂₅(SR)₁₈ nanocomposites for catalysis. The synthesis started with atom transfer radical copolymerization of an inimer with a cyclic disulfide-containing methacrylate monomer in a microemulsion to produce hyperbranched copolymers with high molar mass, low polydispersity, and a vital fraction of dangling disulfide groups. The core-shell structured hyperstar polymers were then prepared using hyperbranched copolymers as macroinitiators to polymerize oligo(ethylene glycol) methyl ether methacrylate (M_n = 500) and grow the radiating arms. The hyperstar polymers with disulfide groups were proved to efficiently encapsulate Au₂₅(SR)₁₈ nanoclusters through ligand exchange without destroying the fine structure of the Au₂₅(SR)₁₈ clusters. The obtained hyperstar-Au₂₅(SR)₁₈ nanocomposites showed great stability with no size change after a three-month shelf storage. They were used as efficient catalysts for the catalytic reduction of 4-nitrophenol by NaBH₄, showing convenient recovery and reuse without losing catalytic efficiency.