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

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 Au⁰ particles was very essential for the fabrication of AuNPs-HG in terms of hydrogel pore size, Au⁰ 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. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48653.