AuNPs composites of gelatin hydrogels crosslinked by ferrocene‐containing polymer as recyclable supported catalysts

Abstract

To fabricate a recyclable supported catalyst based on gold nanoparticles (AuNPs) and gelatin hydrogel (HG) composites, a ferrocene (Fc)-containing tetrablock copolymer [P(NCHO-b-NFc-b-NTEG-b-NCHO)] was used as both reducing and stabilizing agents for AuNPs and as a crosslinker for HG. First, the effects of Fc-containing polymers, including homopolymer PNFc and copolymer P(NCHO-b-NFc-b-NTEG-b-NCHO), and different solvent systems on the morphology and aggregation of AuNPs were examined by using ultraviolet-visible spectroscopy, transmission electron microscopy, and dynamic light scattering. Second, two strategies (blending and soaking) were applied to prepare different AuNPs/HG composites (AuNPs-HG), and their structure and properties were studied by using various techniques including scanning electron microscopy, X-ray diffraction, and thermogravimetry. Finally, the catalytic performance and reusability of AuNPs-HG-1 (via blending) and AuNPs-HG-2 (via soaking) were evaluated utilizing the model catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH 4 . Results indicated that P(NCHO-b-NFc-b-NTEG-b-NCHO) dissolved in N,Ndimethylformamide was the optimal reductant and stabilizer to prepare AuNPs. The in situ reduction of Au III ions to Au 0 particles was very essential for the fabrication of AuNPs-HG in terms of hydrogel pore size, Au 0 distribution and immobilization stability, and hydrogel thermal stability. Due to the stronger interactions among AuNPs, P(NCHO-b-NFc-b-NTEG-b-NCHO), and gelatin molecules in the blending strategy, AuNPs-HG-1 showed better mechanical stability and catalytic performance and more reusing cycles than AuNPs-HG-2. This work highlights the design and fabrication of robust recyclable supported AuNP catalyst by using eco-friendly Fccontaining HGs.

Insights into the interaction between PANI and Au NPs of magnetic core‐shell Fe3O4/PANI/Au catalysts with remarkable catalytic performance in 4‐NP reduction

“…Because that the dosage of NaBH 4 exceeds greatly than that of 4‐NP, the reduction reaction can be regarded as pseudo‐first‐order reaction. The apparent rate constant k is calculated from the equation: where C t /C 0 represents the ratio of 4‐NP concentrations at time t and 0, which is calculated from their corresponding absorption intensity in UV–Vis spectra 33 . The linear fit of ln ( C t / C 0 ) versus time t with Fe 3 O 4 /PANI/Au(Sol) ( k = 0.04771 s −1 ) and Fe 3 O 4 /PANI/Au(In Situ) ( k = 0.02296 s −1 ) as catalysts is shown in Figure 5c.…”

Aluminum tanning of hide powder and skin pieces under microwave irradiation

“…The first weight-loss mainly occurs at 50-120°C, too, and the corresponding mass-loss ratios are 21.8% for the MWH sample and 19.1% for the WBH control, respectively. This mainly results from the removal of H 2 O and other volatile small-size substances in tanned skin pieces [45]. The obvious weight-loss process on the TG curves is the second stage from 200 to 500°C, which mainly resulted from the break of cross-linking bonds between collagen fibers [41].…”

ROMP of supramolecular norbornene monomers containing β-cyclodextrin–ferrocene (/adamantane) inclusion complexes

“…In particular, all kinds of ferrocene (Fc)-containing polymers with precise structures and MWs can also be controllably prepared through the direct ROMP of Fc-containing norbornene-based monomers under the initiation of the third-generation Grubbs' catalyst [21]. It was confirmed that the presence of the sandwich-like Fc complex has no effect on the catalytic activity of Grubbs' catalyst, leading to molecular level control of the resulting polymers and materials for various functional applications [22,23]. However, the direct ROMP of supramolecular monomers, for example, those containing host-guest complexes of β-cyclodextrin (β-CD)/Fc, is still a major challenge [24].…”