Shape and Size Regulation of Gold Nanoparticles by Poly(N,N-diethylacrylamide) Microgels

Abstract

We demonstrated the effect of poly(N,N-diethylacrylamide) (PDEAAm) microgels on the regulation of shape and size of gold nanoparticles (Au NPs), which were prepared by reduction of Au ion adsorbed on PDEAAm microgels. The reaction solvent used for the reduction changed the swelling state of the microgels to affect the shape of the Au NPs. In addition, the size of Au NPs could be regulated by adsorbed amount of Au ion in the microgels and the crosslinking density of the microgels.Keywords: Au nanoparticle | PDEAAm microgel | Polymer stabilizerMetal nanoparticles (NPs) have garnered much attention due to their unique electronic, optical, magnetic, and catalytic properties, which are distinct from those of the bulk metals. 13For example, gold NPs (Au NPs) show beautiful color due to surface plasmonic resonance and exhibit excellent catalytic activity in various chemical reactions such as oxidation and reduction, whereas bulk Au cannot catalyze these reactions. 47Such unique properties of metal NPs are intrinsically determined by their shape and size.714 Therefore, the regulation of shape and size of NPs is important for the development of metal NP materials.One of the most useful methods to regulate the shape and size of metal NPs is using polymer stabilizers during the reduction of the metal ion in solution. Polymer stabilizers can coordinate and adsorb to metal ion and NPs by multidentate interaction of each monomer unit, and suppress the aggregation of metal NPs. Furthermore, this interaction of polymers sometimes occurred at the specific crystal surface of NPs and regulates the direction of crystal growth to produce anisotropic NPs.1416 For example, Xia et al. reported the preparation of Ag nanowires by the so-called polyol process, which conducts reduction of Ag ion in the presence of poly(vinylpyrrolidone). 15In a similar way, octahedral Au NPs can be obtained by using poly(diallyldimethylammonium chloride) in the reduction of Au ions.14 Thermoresponsive poly(N-isopropylacrylamide) was also examined to prepare anisotropic Pt NPs such as cubic and triangular. 16 Thus, the reduction of metal ions in the presence of specific polymers can produce metal NPs with various shapes and sizes.Not only linear polymers but also three-dimensional polymer networks, i.e. polymer gels, are attractive as additives for the preparation of metal NPs.1721 Polymer gels have unique internal space, which can be utilized for stabilizing metal NPs. In addition, the characteristics of polymer gels can affect the functions of the metal NPs. Notably, stimuli-responsiveness of the polymer gels would be important for the development of smart materials by the combination of NPs and gels. Such a feature of the obtained composite of gels and metal NPs is fascinating, especially as a gel catalyst, because of their stability and recyclability. 2023 In addition, the network structure of the polymer gels can be easily tuned by selecting monomer structure and changing the ratio of monomer and crosslinker. Such control of the network structure is p...

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Effect of Gold Nanoparticle Size on Regulated Catalytic Activity of Temperature-Responsive Polymer−Gold Nanoparticle Hybrid Microgels

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Controllable Catalytic Activity of Temperature-Responsive Polymer Hybrid Microgels Designed Using a Gold Nanoparticle Monomer with Polymerizable Groups

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