Silver/Polystyrene Nanocomposites: Optical and Thermal Properties Vesna Vodnik, 1 Dus ˇ an K. Boz ˇ anic ´, 1 Jasna V. Dz ˇ unuzovic ´, 2 Ivana Vukoje, 1 Jovan Nedeljkovic ´ 1 1 Vinc ˇa Institute of Nuclear Sciences, University of Belgrade, 11001 Belgrade, Serbia 2 Institute of Chemistry, Technology and Metallurgy (ICTM)-Center of Chemistry, University of Belgrade, 11000 Belgrade, Serbia Nanocomposites consisted of different quantities of silver (Ag) nanoparticles incorporated in a polystyrene (PS) matrix have been prepared by solution mixing method. Transmission electron microscopy was applied to determine the size distribution of the Ag nanoparticles, while the morphology of fractured surfa- ces of pure PS and Ag/PS nanocomposites was exam- ined by scanning electron microscopy. Absorption spectra of nanocomposites were compared with theo- retically calculated spectra based on the Maxwell-Gar- nett effective medium theory. The influence of Ag con- tent on thermal properties of Ag/PS nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry. Thermal and thermo- oxidative stability of the host polymer were improved by introduction of silver nanoparticles. The glass tran- sition temperature of the prepared Ag/PS nanocompo- sites was lower in comparison with the neat PS and decreased with the increase of the Ag content due to the very weak interfacial interaction between Ag nano- particles and polymer matrix. POLYM. COMPOS., 33:782– 788, 2012. ª 2012 Society of Plastics Engineers INTRODUCTION Polymer nanocomposites made from stable and uniform nanoparticles, well dispersed in carefully selected polymer matrix exhibit improved properties in comparison to the neat polymer or polymer composites obtained by conven- tional technologies. These reinforced materials combine typical properties of polymers with interesting electrical, optical, catalytic, magnetic, and other useful properties of metal nanoparticles and constantly receive great attention because of huge field of possible diverse commercial appli- cations [1–3]. Such strong reinforcing effect obtained by addition of small amount of nanoparticles is mainly a con- sequence of their very large surface area, which in combi- nation with adequate and controlled particle size, regular shape, and uniform nanofiller dispersion in polymer matrix provides big interfacial polymer/particles area, modifying in this manner certain properties of the polymer matrix. The main task in polymer nanocomposite technology is the prevention of particle aggregation, which occurs because of their high surface energy. This problem can be over- come by adequate modification of the particle surface, which can improve and adjust the interfacial interactions between inorganic particles and polymer matrix [4]. The silver nanoparticles are frequently used as nanofillers for different polymer matrices due to their catalytic and anti- microbial activity, good conductivity, chemical stability, and possibility to improve thermal and other properties of the applied host polymer [3, 5–8]. In addition, the improvement of the optical performances of polymers can be achieved by incorporation of the appropriate size silver nanoparticles with strong plasma resonance absorption [6, 9]. A good host for this purpose is polystyrene (PS) since it can provide effective stabilization of Ag nanoparticles and enable processability of thus prepared nanocomposites for designing various devices, in which targeted properties of PS are retained or improved [10]. PS represents a nonabsorbing medium throughout the visible spectrum, whereas the silver nanoparticles absorb light in narrow wavelength range. Therefore, the controlled combination of these two dissimilar materials can lead to the formation of the nanocomposites that display a resonance absorption peak in the visible spectral range. This specific feature and other useful properties of the Ag/PS nanocompo- sites can be used in different functional applications such as in surface enhanced Raman scattering, molecular sensing [9], in biomedicine [11], antimicrobial packaging [12], or for digital memory devices [13]. Various approaches have been successfully developed to prepare Ag/PS nanocomposites, including emulsion polymerization [10, 14], dispersion polymerization [15], reverse micelle, gas antisolvent and ultrasound method Correspondence to: Dr. Vesna Vodnik; e-mail: vodves@vinca.rs Contract grant sponsor: Ministry of Education and Science of the Repub- lic of Serbia; contract grant numbers: 172056, 45020. DOI 10.1002/pc.22207 Published online in Wiley Online Library (wileyonlinelibrary.com). V V C 2012 Society of Plastics Engineers POLYMERCOMPOSITES—-2012