Gold nanoparticles immobilized on porous monoliths obtained from disulfide-based dimethacrylate: Application to supported catalysis Romain Poupart, Benjamin Le Droumaguet * , Mohamed Guerrouache, Daniel Grande, Benjamin Carbonnier Universit e Paris-Est, Institut de Chimie et des Mat eriaux Paris-Est (ICMPE), UMR7182, CNRS-UPEC, 2 Rue Henri Dunant, 94320 Thiais, France article info Article history: Received 21 January 2017 Received in revised form 10 April 2017 Accepted 11 April 2017 Available online xxx Keywords: Macroporous polymeric monolith Disulfide bridge Gold nanoparticles Supported catalysis Dye reduction abstract In this work, we report on the design and synthesis of an original methacrylic monolith bearing selec- tively 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 disul- fide, 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 3þ 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. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction In this era of great efforts towards the development of more and more eco-friendly processes, heterogeneous supported catalysis appears as an appealing field of research due to actual ever- growing environmental concerns/requirements [1,2]. Among this field, nanometal-based catalysis has gained a tremendous interest, as supported nanometals present unique properties compared to their bulk material counterparts that make them advantageous in different applications. In the broad area of catalysis, gold nano- particles are probably the most commonly used nanometals [3e11]. During the last decade, not only gold [12e14] but also palladium- [15], silver- [16], platinum- [17], and copper-based nanoparticles [18] have been applied to heterogeneous catalysis, even though they were considered a few years ago as chemically inert [19]. Different model catalytic reactions have been so far developed with such nanometal-based systems, including (di)nitroarene [11,12,20,21], hexacyanoferrate [10] or dye reduction [4,5], and even more interesting Suzuki-Miyaura C-C cross-coupling reactions [6] or cascade reactions [22]. However, inherent properties of immo- bilized gold nanoparticles do not restrict them only to the catalysis area but can also have interesting applications in diverse research fields, such as chromatographic supports [23e29], antibacterial systems [30], drug delivery devices [31], sensors [32,33] and pho- tovoltaics [34], supported biocatalysts [35] as well as Surface Enhanced Raman Spectroscopy (SERS) [36]. Thiol functions are prone to chelate gold and are generally used to anchor them in a covalent-like manner [24]. Unfortunately, thiols are also well-known to easily produce corresponding disulfide bridges under mild oxidizing conditions, such as under O 2 atmo- sphere, thus presenting a serious limitation to their use. However, disulfide moieties (-S-S-) can be selectively cleaved by using appropriate chemical reducing agents, such as phosphine de- rivatives [12,37] or dithiothreitol (DTT) [38], to cite but a few, thus being considered as protected thiols. Recently, polymeric materials bearing such disulfide bridges have largely been used in diverse applications [18,39,40], mainly because of the straightforward introduction of such chemical functions within the backbone or the * Corresponding author. E-mail address: ledroumaguet@icmpe.cnrs.fr (B. Le Droumaguet). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer http://dx.doi.org/10.1016/j.polymer.2017.04.034 0032-3861/© 2017 Elsevier Ltd. All rights reserved. Polymer xxx (2017) 1e8 Please cite this article in press as: R. Poupart, et al., Gold nanoparticles immobilized on porous monoliths obtained from disulfide-based dimethacrylate: Application to supported catalysis, Polymer (2017), http://dx.doi.org/10.1016/j.polymer.2017.04.034