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

摘要

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 NaBH4. Results indicated that P(NCHO-b-NFc-b-NTEG-b-NCHO) dissolved in N,N-dimethylformamide 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 Fc-containing HGs. (C) 2019 Wiley Periodicals, Inc.