Fabrication of Silver Nanoparticles in Hydrogel Networks a Y. Murali Mohan, Thathan Premkumar, Kyungjae Lee, Kurt E. Geckeler* Laboratory of Applied Macromolecular Chemistry, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea E-mail: keg@gist.ac.kr Received: April 28, 2006; Revised: June 20, 2006; Accepted: June 21, 2006; DOI: 10.1002/marc.200600297 Keywords: crosslinking; hydrogels; poly(N-isopropylacrylamide); poly(sodium acrylate); silver nanoparticles Introduction Metal nanoparticles and nanostructured materials are novel classes of materials, [1] which have attracted great attention in catalysis, [2–5] optics, [6,7] electronics, [8,9] and biomedi- cine [1,2] as well as quantum-size domain applications [10,11] due to their unusual physicochemical properties that are quite different from those of the bulk solids. The synthesis of metal nanoparticles is a major research area in nano- science and technology. Chemical reduction via micro- emulsion, [12] co-precipitation, [13,14] carbon nanotubes [15] and polymer protection [16–18] has been extensively used as the best way to obtain metal nanoparticles with a narrow size distribution. Many approaches indicate that, despite simple organic polymer templates including biological macromolecules, [19,20] block copolymers, [21,22] dendri- mers, [23–25] liquid crystals, [26] latex particles, [27] meso- porous inorganic materials, [28] microgels [29] and hydro- gels [30,31] can produce well defined morphologies of the metal nanoparticles. Recent research efforts have been Summary: This paper describes a simple and facile approach to fabricate well dispersed silver nanoparticles (AgNPs) in poly[N-isopropylacrylamide-co-(sodium acrylate)] hydro- gels. The silver nanoparticles formed are spherical in shape with a narrow size distribution in the hydrogel networks in which the nanoparticles are stabilized by the polymer net- work. Uniformly dispersed silver nanoparticles were obtain- ed with poly[N-isopropylacrylamide-co-[sodium acrylate)] hydrogels, whereas a poly(N-isopropylacrylamide)/poly(so- dium acrylate) IPN gel showed aggregated nanoparticles. It is demonstrated that the hydrogel network structure determines the size and shape of the nanoparticles. These particles are more stable in the gel networks compared to other reduction methods. The hydrogel/silver nanohybrids were well char- acterized by XRD, UV-vis spectrometry, scanning electron microscopy and transmission electron microscopy. Schematic representation of the preparation of Ag nanoparticles in hydrogel networks. Macromol. Rapid Commun. 2006, 27, 1346–1354 ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1346 DOI: 10.1002/marc.200600297 Communication a : Supporting information for this article is available at the bottom of the article’s abstract page, which can be accessed from the journal’s homepage at http://www.mrc-journal.de, or from the author.