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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 Au 3+ ions. Subsequent hydride-mediated reduction of the latters in the presence of NaBH 4 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. [ABSTRACT FROM AUTHOR]

This paper addresses the functionalization of doubly porous poly(2-hydroxyethyl methacrylate) (PHEMA)-based networks obtained from the double porogen approach, and their subsequent utilization as catalytic supports in heterogeneous catalysis. Advantage of the availability of hydroxyl groups within the PHEMA-based frameworks was taken through a chemical modification with carbonyldiimidazole. This key activation led to three main functionatization reactions of the materials via nucleophilic substitution or thiol-yne 'click' addition of amino molecules. Further, in-situ generation of gold nanoparticles (GNPs) allowed for the preparation of innovative functionalized biporous GNP@PHEMA materials. The as-obtained hybrid frameworks could efficiently be used as catalytic supports in the reduction of 4-nitrophenol. [ABSTRACT FROM AUTHOR]

Monoliths functionalized with ethylene diamine-derived ligands were synthetized within micro-sized channels as highly permeable catalytic supports for the immobilization of in-situ generated gold nanoparticles. The as-obtained hybrids, essentially differing on the grafted amine-containing ligands were compared, notably regarding the immobilized nanoparticles morphology and their dispersion at the monolith pore surface. Further, such in-capillary hybrid monoliths were successfully applied as flow-through microreactors for the catalytic reduction of nitroaromatic compounds. The general synthetic route for preparing these composite materials consisted in a three-step procedure involving (i) UV-induced polymerization of N -acryloxysuccinimide and ethylene glycol dimethacrylate in toluene, (ii) surface grafting of a series of ethylene diamine derivatives through nucleophilic substitution of N -hydroxysuccinimide leaving groups, and (iii) successive in situ reduction of tetrachloroauric acid to generate monolith-adsorbed gold nanoparticles. The successful synthesis of such hybrid monoliths was ascertained by in-situ Raman spectroscopy, EDX analysis and SEM observations. Microscopy demonstrated the key role of the grafted amine-bearing ligand regarding the morphology, size and surface coverage of the immobilized gold nanoparticles at the monolith pore surface. Monolith-adsorbed gold nanoparticles exhibited good catalytic activities towards the conversion of nitroaromatic compounds into the corresponding amino derivatives in a flow-through process. This study clearly demonstrates the key role of the nature, primary vs. secondary, of the chelating amine in the morphology (shape, size, dispersion) of the supported gold nanoparticles. [Display omitted] • In situ synthesis of hybrid porous polymer-nanoparticle composites within microchannels. • One-step functionalization of the monoliths with amine-containing chelatants of varied chemical nature and topology. • Dispersion, size and morphology of nanogold depend on the nature of the surface-grafted amine. • Successful continuous flow catalytic reduction of nitroarenes using porous polymer-nanoparticle composites as microreactors. [ABSTRACT FROM AUTHOR]