Synthesis of Nanocomposites from Pd⁰ and a Hyper‐Cross‐Linked Functional Resin Obtained from a Conventional Gel‐Type Precursor

Abstract

Hyper-cross-linked resins stemming from a gel-type poly-chloromethylated poly(styrene-co-divinylbenzene) resin (GT) have been investigated by a multi-methodological approach based on elemental analysis, scanning electron microscopy, X-ray microanalysis, and solvent absorption. The hyper-cross-linking of the parent resin was accomplished by Friedel-Crafts alkylation of the phenyl rings of the resins with the chloromethyl groups. This produced a permanent pore system comprising both micropores (<2.0 nm in diameter) and mesopores (2.2 nm). The chloromethyl groups that did not react in the hyper-cross-linking step were transformed into methylmercaptan groups and the latter were then converted into sulfonic groups by oxidation with hydrogen peroxide. By this procedure the extensive permanent porosity of the parent unsulfonated hyper-cross-linked polymer (HGT) was retained by the sulfonated polymer (HGTS). The final exchange capacity of HGTS was determined to be 0.36 mmol g(-1). HGTS was easily metalated with Pd(II) and the subsequent reduction of the metal centers with either aqueous sodium borohydride, formaldehyde, or dihydrogen produced three Pd(0)/HGTS nanocomposites. The metal nanoparticles had diameters in the 1-6 nm range for all the nanocomposites, as determined by TEM, but with somewhat different distributions. When formaldehyde was used, more than 90% of the nanoparticles were less than 3 nm and their radial distribution throughout the polymer beads was quite homogeneous. These findings show that with this reducing agent the metal nanoparticles are generated within the pore system of the polymer matrix, hence their size is controlled by the dimensions of the pores of the polymeric support.

Polyphenylene sulfide‐based adsorption resins: synthesis, characterization and adsorption performance for Hg(II) and As(V)

“…The decomposition temperature of PPS‐based ion exchange and chelating resins are about 200°C or more, the residues can maintain more than 50%, but polystyrene resin decomposition temperature is 120–180°C, thermal decomposition residues are less than 40% , . PPS‐Based ion exchange and chelating resins are superior to the resin of the polystyrene skeleton in stability.…”

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

“…Hence, our new materials benefit from significant advantages. Considering that polystyrenes have been used also as supporting materials for nanosized inorganic species such as copper oxide [54] or noble metals (Pt [55] and Pd [56]) able to catalyze organic reactions, our nanosponges undoubtedly appear as promising new platforms for the preparation of composite nanocatalysts or functional materials with improved performances.…”

Influence of Metal Precursors and Reduction Protocols on the Chloride‐Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers

“…In general, a poor relationship was observed between the average size of Pd nanoparticles in the hydrogen‐reduced catalysts 1PdK/S/H, 1PdK/N/H, and 1PdK/A/H and the pore size in K2621 swollen in THF, which is the solvent employed in the reduction stage. This is different from what is usually observed with gel‐type resins and hyper‐cross‐linked resins, in which the reduction of the metal precursors and the formation of the nanoparticles takes place inside the swollen polymer framework or in permanent, very small mesopores so that the size of the nanoparticles is strictly comparable with the pore diameters in the polymer mass . Apparently, the polymer framework of K2621 did not swell in THF: no gel phase was detected by inverse size‐exclusion chromatography (ISEC; Table S2).…”

“…This suggests that the reduction of Pd II occurred on the surface of the mesopores of the resin, which had diameters of 13 and 43 nm. These sizes are too large to give the effective control of the nanoparticle size observed with swollen gel‐type resins or hyper‐cross‐linked resins . Hence, the final size of the metal nanoparticles is expected to be controlled only by the kinetics of their formation .…”