Macromolecular Nanotechnology Thermal and optical properties of silver–poly(methylmethacrylate) nanocomposites prepared by in-situ radical polymerization V.V. Vodnik a , D.K. Boz ˇanic ´ a , E. Dz ˇunuzovic ´ b , J. Vukovic ´ c , J.M. Nedeljkovic ´ a, * a Vinc ˇa Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia b Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia c Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, University of Belgrade, Njegoševa 12, Belgrade, Serbia article info Article history: Received 23 July 2009 Received in revised form 15 October 2009 Accepted 24 October 2009 Available online 29 October 2009 Keywords: Silver nanoparticles PMMA Nanocomposite In-situ radical polymerization Maxwell-Garnet theory Thermal stability abstract Surface modified silver nanoparticles dispersed in chloroform were encapsulated in poly(methylmethacrylate) (PMMA) by in-situ radical polymerization of methyl methacry- late initiated by 2,2 0 -azobisisobutyronitrile. The particle size distribution of colloidal silver nanoparticles was determined using transmission electron microscopy. The obtained transparent nanocomposite films were characterized using UV–vis spectroscopy, 1 H NMR spectroscopy and gel permeation chromatography. Effective medium Maxwell-Garnett theory was used in order to explain optical properties of nanocomposite films taking into account inhomogeneous spatial distribution of silver nanoparticles in PMMA matrix. The influence of the silver nanoparticles on the thermal properties of the PMMA matrix was investigated using thermo-gravimetric analysis and differential scanning calorimetry. Thermo-oxidative stability of the PMMA in the presence of low content of inorganic phase is significantly improved. The glass transition temperatures of nanocomposites are slightly lower compared to the pure polymer. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Polymers are considered to be a good host for inorganic nanoparticles. Incorporation of inorganic nanoparticles due to their high-surface to bulk ratio can significantly af- fect the properties of the polymer matrix [1,2]. The ob- tained nanocomposites might exhibit improved optical, thermal, mechanical, electrical, magnetic and flammability properties [3–12]. The properties of polymer composites depend on type of incorporated nanoparticles, their size and shape, their concentration and interaction with poly- mer matrix. Different synthetic procedures for preparation of silver/ poly(methylmethacrylate) (Ag/PMMA) composites have been described in literature: ‘‘shell–core” synthesis [13,14], ion implantation [15,16], vapor phase co-deposi- tion in vacuum [17] and suspension polymerization [18]. The main problem in polymer nanocomposite technology is the prevention of particle aggregation. This problem can be overcome by surface modification of the particles. The modification improves the interfacial interaction be- tween the inorganic particles and the polymer matrix [1,19,20]. In this study, we used simple procedure for prep- aration of Ag/PMMA nanocomposites. Highly uniform sil- ver nanoparticles synthesized in water were surface modified and by phase transfer process extracted into non-polar organic solvent. In the second step, nanocom- posites were prepared by in-situ bulk polymerization of methyl methacrylate in the presence of appropriate amount of silver nanoparticles. Among polymeric materi- als, PMMA is well known as a polymeric glass and engi- neering plastic with a wide range of applications. One of the objectives of this paper is to gain better insight into the properties of this material upon incorporation of small amount of silver nanoparticles. Because of that, the 0014-3057/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2009.10.022 * Corresponding author. Address: Vinc ˇa Institute of Nuclear Sciences, Laboratory for Radiation Chemistry and Physics, P.O. Box 522, 11001 Belgrade, Serbia. Tel.: +381 11 243 8906; fax: +381 11 344 2420. E-mail address: jovned@vinca.rs (J.M. Nedeljkovic ´). European Polymer Journal 46 (2010) 137–144 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj MACROMOLECULAR NANOTECHNOLOGY