Gold nanoparticles immobilized on porous monoliths obtained from disulfide-based dimethacrylate: Application to supported catalysis

In this work, we report on the design and synthesis of an original methacrylic monolith bearing selectively cleavable disulfide bridges. One such monolith was prepared by thermally-induced free-radical copolymerization using a disulfide-based labile dimethacrylate, i.e. bis(2-methacryloyl)oxyethyl disulfide, and ethylene glycol dimethacrylate as comonomers, as well as toluene as a porogenic solvent. Upon dithiothreitol-mediated reduction of the disulfide moieties within the as-obtained disulfide-bearing monolith, thiol functions were formed at the pore surface of the resulting monolith, which was confirmed by means of in-situ Raman spectroscopy, while the pore size distribution was analyzed by mercury intrusion porosimetry. Immersion of the thiol-functionalized porous material in a chloroauric acid solution allowed for successful chelation of Au3+ ions. Subsequent hydride-mediated reduction of the latters in the presence of NaBH4 gave rise to the generation of gold nanoparticles (AuNPs) that were immobilized at the monolithic pore surface The efficiency of this hybrid material based on AuNPs@porous monolith as a heterogeneous supported catalyst was further demonstrated through the reduction of a relatively toxic dye commonly used in textile and dye industries, i.e. Eosin Y. Notably, no loss of catalytic activity was observed by using this hybrid supported catalyst after 6 consecutive runs. (C) 2017 Elsevier Ltd. All rights reserved.